Low-friction, small profile medical tools having easy-to-assemble components

ABSTRACT

A low-friction medical device includes a first link, a second link, and a tension member. The first link is coupled to an instrument shaft and a first guide path is defined in the first link. The second link is rotatable relative to the first link through an angular range. A distal end portion of the second link is rotatably coupled to a tool member. A curved guide path is defined within the second link between the tool member and the first guide path. A curved guide surface of the second link defines a portion of the second guide path. A first portion of the tension member is parallel to a centerline of the first guide path, and a second portion is coupled to the tool member. A third portion of the tension member between the first and second portions is in contact with the curved guide surface throughout a portion of the angular range.

RELATED APPLICATIONS

This patent application is a continuation of U.S. application Ser. No.16/971,982 (filed Aug. 21, 2020) (entitled “LOW-FRICTION, SMALL PROFILEMEDICAL TOOLS HAVING EASY-TO-ASSEMBLE COMPONENTS”), which is a U.S.national stage filing under 35 U.S.C. § 371 of International ApplicationNo. PCT/US2019/020653 (filed Mar. 5, 2019) (entitled “LOW-FRICTION,SMALL PROFILE MEDICAL TOOLS HAVING EASY-TO-ASSEMBLE COMPONENTS”), whichclaims priority to and the filing date benefit of U.S. ProvisionalPatent Application No. 62/639,631 (filed Mar. 7, 2018) (entitled“LOW-FRICTION, SMALL PROFILE MEDICAL TOOLS HAVING EASY-TO-ASSEMBLECOMPONENTS”), each of which is incorporated by reference herein in itsentirety.

BACKGROUND

The embodiments described herein relate to grasping tools, morespecifically to medical devices, and still more specifically toendoscopic tools. More particularly, the embodiments described hereinrelate to low-friction tools and devices that include roller-assistedtension members that can be used, for example, in surgical applications.

Known techniques for Minimally Invasive Surgery (MIS) employ instrumentsto manipulate tissue that can be either manually controlled orcontrolled via computer-assisted teleoperation. Many known MISinstruments include a therapeutic or diagnostic end effector (e.g.,forceps, a cutting tool, or a cauterizing tool) mounted on a wristmechanism at the distal end of an extension (also referred to herein asthe main tube or shaft). During an MIS procedure, the end effector,wrist mechanism, and the distal end of the main tube can be insertedinto a small incision or a natural orifice of a patient to position theend effector at a work site within the patient's body. The optionalwrist mechanism can be used to change the end effector's orientationwith respect to the main tube to perform the desired procedure at thework site. Known wrist mechanisms generally provide the desired degreesof freedom (DOFs) for movement of the end effector. For example, forforceps or other grasping tools, known wrist mechanisms are often ableto change the pitch and yaw of the end effector with reference to themain tube. A wrist may optionally provide a roll DOF for the endeffector, or the roll DOF may be implemented by rolling the main tube.An end effector may optionally have additional mechanical DOFs, such asgrip or knife blade motion. In some instances, wrist and end effectormechanical DOFs may be combined. For example, U.S. Pat. No. 5,792,135(filed May 16, 1997) discloses a mechanism in which wrist and endeffector grip DOFs are combined.

To enable the desired movement of the wrist mechanism and end effector,known instruments include tension members (e.g., cables, cable/hypotubecombinations, tension bands) that extend through the main tube of theinstrument and that connect the wrist mechanism to a transmission (alsoreferred to herein as a backend mechanism). The backend mechanism movesthe cables to operate the wrist mechanism. For teleoperated systems, thebackend mechanism is motor driven and can be operably coupled to aprocessing system to provide a user interface for a doctor to controlthe instrument.

Patients benefit from continual efforts to improve the effectiveness ofMIS methods and tools. For example, reducing the size and/or theoperating footprint of the main tube and wrist mechanism can allow forsmaller entry incisions, thereby reducing the negative effects ofsurgery, such as pain, scarring, and undesirable healing time. But,producing small diameter medical instruments that implement theclinically desired functions for minimally invasive procedures can bechallenging. Specifically, simply reducing the size of known wristmechanisms by “scaling down” the components will not result in aneffective solution because required component and material properties donot scale. For example, efficient implementation of a wrist mechanismcan be complicated because the cables must be carefully routed throughthe wrist mechanism to maintain cable tension throughout the range ofmotion of the wrist mechanism and to minimize the interactions (orcoupling effects) of one rotation axis upon another. Further, pulleysand/or contoured surfaces are generally needed to reduce cable friction,which extends instrument life and permits operation without excessiveforces being applied to the cables or other structures in the wristmechanism. Increased localized forces that may result from smallerstructures (including the cables and other components of the wristmechanism) can result in undesirable lengthening (e.g., “stretch” or“creep”) of the cables during storage and use, reduced cable life, andthe like.

Further, some medical instruments have end effectors that requireelectrical energy for clinical functions such as desiccation,hemostasis, cutting, dissection, fulguration, incisions, tissuedestruction, cauterizing, and vessel sealing. Accordingly, knowninstruments include one more conductors routed through the wristmechanism to the portion of an end effector to be energized. Fitting allthe components of the wrist mechanism, drive cables, and conductivewires into a small diameter, for example, less than about 10 mm, whilepreserving the necessary strength and function of these components canbe difficult.

In addition to reducing the size of medical instruments, it is alsodesirable to develop low-cost instruments that are effectivelydisposable (i.e., that are intended for a single use only at an economiccost). With such instruments, each MIS procedure can be performed with anew, sterilized instrument, which eliminates cumbersome and expensiveinstrument reuse cleaning and sterilization procedures. Many currentinstrument designs are expensive to produce, however, and so for economythese instruments undergo sterile reprocessing for use during multiplesurgical procedures. In part, the cost of these instruments may be dueto multiple-strand tungsten cables and hypotube portions to withstandthe operating loads.

In some instances, known wrist mechanisms make use of multiple pairs ofcables to provide control for moving the wrist mechanism in variousranges of motion including yaw, pitch and roll movements of the wristmechanism with reference to the main tube. These conventional wristmechanisms use a pair of pitch cables that are coupled together to forma cable loop to provide pitch control for the wrist mechanism. Therouting for each of the individual cables in such known wrist mechanismscan enhance pitch control, but may also restrict movement of the pitchcables during pitch movements and increase friction associated withactuating pitch movements. Further, the inclusion of cable guidance andconnection features of these mechanisms may also increase the size ofthe wrist mechanism or make it difficult to reduce its size andfootprint.

In addition, known wrist mechanisms can be difficult to assemble. Forexample, assembly procedures for some known wrist mechanisms can includeperforming cable crimping procedures to axially connect a pair of cablesto each other to form a cable loop, and then coupling the cable pair tothe wrist mechanism with the crimp being retained in a pocket formed inthe wrist mechanism. Although crimping and connecting the cables to eachother prior to installation may avoid damage pertaining to the crimpingoperation, installation of the cable loop, along with installation ofthe attached cable crimp, may complicate installation of the cable loopand increase undesirable bending of or damage to the cable loop duringinstallation.

Thus, a need exists for improved endoscopic tools. Improvements mayinclude wrist mechanisms having reduced size, reduced part count, lowercost of materials, and increased-strength tension members operating withlow friction during use. In addition, improvements may permit easyassembly, including installation of tension members in wrist mechanismsto axially connect two or more individual tension members while avoidingadversely impacting the integrity of the tension members from bending,twisting, or other actions during installation.

SUMMARY

This summary introduces certain aspects of the embodiments describedherein to provide a basic understanding. This summary is not anextensive overview of the inventive subject matter, and it is notintended to identify key or critical elements or to delineate the scopeof the inventive subject matter.

In some embodiments, a low-friction medical device includes a firstlink, a second link, and a tension member. The first link is coupled toan instrument shaft and defines a first guide path therein. The secondlink has a proximal end portion and a distal end portion. The secondlink is rotatable relative to the first link through an angular range.The distal end portion of the second link is coupled to a tool member,and the tool member is rotatable relative to the second link about asecond axis. A second guide path is defined within the second linkbetween the tool member and the first guide path. The second linkincludes a curved guide surface that defines a portion of the secondguide path. The tension member has a first tension member portion, asecond tension member portion, and a third tension member portionbetween the first tension member portion and the second tension memberportion. The first tension member portion is within the first guidepath, and the second tension member portion is coupled to the toolmember. The third tension member portion is in contact with the curvedguide surface throughout a portion of the angular range. The firsttension member portion is parallel to a centerline of the first guidepath.

In some embodiments, a low-friction medical device includes a firstlink, a second link, and a tension member. The first link is coupled toan instrument shaft and defines a first guide path. The second link iscoupled to the first link and is rotatable relative to the first linkabout a first axis. The second link defines a second guide path, aretention pocket, a connection path and an assembly path. The connectionpath extends through a portion of the second link between the secondguide path and the retention pocket. A wall of the second link surroundsa portion of the connection path. A connection path centerline and acenterline of the second guide path define a first plane within thesecond link. The assembly path extends through the portion of the secondlink into the retention pocket. A centerline of the assembly path isnonparallel to the connection path centerline within a second plane thatis nonparallel to the first plane. The tension member has a firsttension member portion, a second tension member portion and a retentionmember coupled to the second tension member portion. The first tensionmember portion is configured to be: (A) inserted through the assemblypath along the assembly path centerline, and (B) rotated until the firsttension member portion is within the second guide path. The retentionmember is retained within the retention pocket after the first tensionmember portion is rotated such that movement of the tension memberrelative to the second link is limited. The second link is configured torotate relative to the first link about the first axis when the firsttension member portion is moved within the second guide path.

Other medical devices, related components, medical device systems,and/or methods according to embodiments will be or become apparent toone with skill in the art upon review of the following drawings anddetailed description. It is intended that all such additional medicaldevices, related components, medical device systems, and/or methodsincluded within this description be within the scope of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a minimally invasive teleoperated medicalsystem according to an embodiment, being used to perform a medicalprocedure such as surgery.

FIG. 2 is a perspective view of an optional auxiliary unit of theminimally invasive teleoperated surgery system shown in FIG. 1.

FIG. 3 is a perspective view of a user control console of the minimallyinvasive teleoperated surgery system shown in FIG. 1.

FIG. 4 is a front view of a manipulator unit, including a plurality ofinstruments, of the minimally invasive teleoperated surgery system shownin FIG. 1.

FIG. 5 is a diagrammatic perspective view of a portion of an instrumentof a surgery system in a first position, according to an embodiment.

FIG. 6A is a diagrammatic top view of the portion of the instrumentshown in FIG. 5 in the first orientation.

FIG. 6B is an enlarged view of a portion of the instrument shown in FIG.5 by the region H shown in FIG. 6A.

FIG. 7 is a diagrammatic top view of the portion of the instrument shownin FIG. 5 in a second orientation.

FIGS. 8A-8B are diagrammatic illustrations of a portion of an instrumentsystem, according to embodiments.

FIG. 9 is a perspective view of an instrument of a surgery system in afirst orientation, according to an embodiment.

FIG. 10 is an enlarged perspective view of a distal end portion of theinstrument indicated by the region Z shown in FIG. 9.

FIG. 11 is a perspective view of the distal end portion of theinstrument of FIG. 10 shown in an exploded view.

FIG. 12 is an enlarged perspective of portions of the tension membersshown in FIG. 11.

FIG. 13 is a perspective view of the distal end portion of theinstrument of FIG. 10 shown with the second link removed to exposeportions of the tension members.

FIG. 14A is a side view of the distal end portion of the instrument ofFIG. 10 in a first orientation, taken along line Y-Y shown in FIG. 9,and shown with the first link and the tension members removed to exposeportions of the guide paths.

FIG. 14B is an enlarged side view of a distal end portion of theinstrument of FIG. 10 in the first orientation, indicated by the regionK shown in FIG. 14A.

FIG. 15A is a top view of the distal end portion of the instrument ofFIG. 10 in a first orientation.

FIGS. 15B and 15C are enlarged top views of the portions indicated bythe regions L and M shown in FIG. 15A, showing a thimble structure ofthe second link of the instrument of FIG. 10.

FIG. 16A is a cross-sectional view of the distal end portion of theinstrument of FIG. 10, taken along line R-R shown in FIG. 15A.

FIG. 16B is an enlarged cross-sectional view of the distal end portionof the instrument indicated by region S shown in FIG. 16A.

FIG. 17A is a cross-sectional view of the distal end portion of theinstrument of FIG. 10 taken along line R-R shown in FIG. 15A, which isshown in a second orientation.

FIG. 17B is a cross-sectional view of the distal end portion of theinstrument of FIG. 10 taken along line R-R shown in FIG. 15A, which isshown in a third orientation.

FIG. 18 is an enlarged perspective view of a distal end portion ofanother instrument indicated by the region Z shown in FIG. 9, accordingto an embodiment.

FIG. 19 is a side view of the distal end portion of the instrument ofFIG. 18 in a first orientation, taken along line Y-Y shown in FIG. 9.

FIG. 20 is a side view of the distal end portion of the instrument ofFIG. 18 in a first orientation and shown with the first link removed toexpose portions of the tension members.

FIG. 21 is a side view of the distal end portion of the instrument ofFIG. 18 in a second orientation and shown with the first link removed toexpose portions of the tension members.

FIG. 22 is a side view of the distal end portion of the instrument ofFIG. 18 showing the second orientation of FIG. 21 superimposed over thefirst orientation of FIG. 20, and both shown with the first link removedto expose portions of the tension members.

FIG. 23 is an enlarged side view of a distal end portion of theinstrument of FIG. 18 in the first orientation indicated by the region Tshown in FIG. 20.

FIG. 24 is an enlarged side view of a distal end portion of theinstrument of FIG. 18 in the second orientation indicated by the regionU shown in FIG. 21.

FIG. 25 is a cross-sectional view of the distal end portion of theinstrument of FIG. 18 in a first orientation, taken along line X-X shownin FIG. 20.

FIG. 26 is a diagrammatic front view of a portion of an instrument of asurgery system in a first orientation, according to an embodiment.

FIG. 27 is a diagrammatic side view of the portion of the instrumentshown in FIG. 26 in the first orientation, as viewed according to lineN-N shown in FIG. 26, and shown without the tension member to exposepaths formed therein.

FIG. 28 is a diagrammatic, cross-sectional view of the portion of theinstrument shown in FIGS. 26 and 27 in the first orientation, takenalong line Q-Q shown in FIG. 27, and shown without the tension member toexpose paths formed therein.

FIG. 29 is a diagrammatic, cross-sectional view of the portion of theinstrument shown in FIGS. 26 and 27 in the first orientation, takenalong line P-P shown in FIG. 27, and shown without the tension member toexpose paths formed therein.

FIG. 30 is a diagrammatic top view of a distal end portion of thetension member of the portion of the instrument shown in FIGS. 26 and27.

FIG. 31A is a diagrammatic top view of a distal end portion of thetension member of the portion of the instrument shown in FIGS. 26 and27, which illustrates installation bends in the tension member as partof an installation method, according to an embodiment.

FIGS. 31B and 31C are diagrammatic, cross-sectional views of the portionof the instrument shown in FIGS. 26 and 27, taken along line P-P shownin FIG. 27, and each shown along with a top view of the distal endportion of the tension member of FIG. 30 to illustrate an installationmethod, according to an embodiment.

FIG. 32 is an enlarged perspective view of a distal end portion of aninstrument in a first orientation, according to an embodiment.

FIG. 33 is an enlarged perspective view of the distal end portion of theinstrument of FIG. 32, shown with some of the tension members, the firstlink, and a pulley removed to expose portions of the second link.

FIG. 34 is an enlarged perspective view of a portion of the instrumentof FIGS. 32 and 33 indicated by the region F shown in FIG. 33.

FIG. 35 is a side view of the distal end portion of the instrument ofFIG. 32 in a first orientation.

FIG. 36 is a side view of the second link of the instrument of FIG. 32in the first orientation.

FIG. 37 is a bottom view of the second link of the instrument of FIG. 32in the first orientation, taken along line V-V shown in FIG. 36.

FIG. 38 is a perspective view of the third tension member of theinstrument of FIG. 32.

FIGS. 39 and 40 are perspective views of the second link of theinstrument of FIG. 32 in the first orientation and portions of a pitchtension member illustrating installation of the pitch tension member.

FIGS. 41 and 42 are top cross-sectional views of portions of the secondlink of the instrument of FIG. 32 and the pitch tension member forinstallation of the pitch tension member shown in FIGS. 38 and 39,viewed from line W-W shown in FIG. 38.

DETAILED DESCRIPTION

The embodiments described herein can advantageously be used in a widevariety of grasping, cutting, and manipulating operations associatedwith minimally invasive surgery. In particular, the instrumentsdescribed herein can be low-cost, disposable instruments that facilitatebeing used for only one procedure. As described herein, the instrumentsinclude one or more cables (which act as tension members) that can bemoved to actuate the end effector with multiple degrees of freedom.Moreover, the cables can include regions having a larger cross-sectionalarea to promote increased strength, or the cables can be wrapped orcurved to allow efficient routing within a miniaturized wrist assembly.

In some embodiments, a low-friction medical device includes a firstlink, a second link, and a tension member. The first link is coupled toan instrument shaft and defines a first guide path therein. The secondlink has a proximal end portion and a distal end portion. The secondlink is rotatable relative to the first link about a first axis throughan angular range. The distal end portion of the second link is coupledto a tool member and the tool member is rotatable relative to the secondlink about a second axis. A curved guide path is defined within thesecond link between the tool member and the first guide path. The secondlink includes a curved guide surface that defines a portion of thesecond guide path. The tension member has a first tension memberportion, a second tension member portion, and a third tension memberportion between the first tension member portion and the second tensionmember portion. The first tension member portion is within the firstguide path, and the second tension member portion is coupled to the toolmember. The third tension member portion is in contact with the curvedguide surface throughout a portion of the angular range. The firsttension member portion is parallel to a centerline of the first guidepath.

In some embodiments, the centerline of the first guide path is offsetfrom a centerline of the shaft by a first distance, and the curved guidesurface is characterized by a radius about the first axis. In suchembodiments, the radius is equal to the first distance. In someembodiments, the centerline of the first guide path is offset from acenterline of the shaft by a first distance, and the curved guidesurface is characterized by a radius of curvature that defines a firstportion of the second guide path. A center of the radius of curvature isoffset from the shaft by a second distance, and the second distance isequal to the sum of the radius of curvature and the first distance.

In some embodiments, the tension member includes a fourth tension memberportion between the first tension member portion and the third tensionmember portion. The fourth tension member portion is parallel to thecenterline of first guide path throughout the angular range. In someembodiments, the curved guide surface of the second link is an outersurface of a pulley coupled to the second link, or the curved guidesurface is a wall of the second link. In some embodiments, the curvedguide surface is a first curved guide surface and the second linkincludes a second curved guide surface. The first curved guide surfaceincludes an outer surface of a pulley coupled to the second link, andforms a first portion of the second guide path. The second curved guidesurface defines a second portion of the second guide path. The portionof the angular range is a first portion, and the third tension memberportion is in contact with the outer surface of the pulley throughoutthe first portion of the angular range. The third tension member portionis in contact with the second curved guide surface throughout a secondportion of the angular range. The fourth tension member portion isparallel to the centerline of the first guide path throughout the firstangular range and the second angular range. In some embodiments, thethird tension member portion is spaced apart from the outer surface ofthe pulley and is in contact with the second curved guide surface whenthe second link is in a first orientation relative to the first link.The third tension member is spaced apart from the second curved guidesurface and is contact with the outer surface of the pulley when thesecond link is in a second orientation relative to the first link.

In some embodiments, the centerline of the first guide path is offsetfrom a centerline of the shaft by a distance, and the outer surface ofthe pulley defines a pulley radius equal to the distance. In someembodiments, the second curved guide surface is characterized by aradius of curvature, and the distance is less than the sum of the pulleyradius and the radius of curvature. In some embodiments, the distance isa second distance, the center of the radius of curvature is offset fromthe centerline of the shaft by a first distance, and the first distanceis equal to the sum of the second distance and the radius of curvature.

In some embodiments, a low-friction medical device includes a firstlink, a second link, and a tension member. A first guide path is definedwithin the first link, and a centerline of the first guide path isoffset from a centerline of the shaft by a distance. The second link hasa proximal end portion and a distal end portion. The proximal endportion of the second link is rotatably coupled to the first link andthe second link is rotatable relative to the first link about a firstaxis through an angular range. The distal end portion of the second linkis rotatably coupled to a tool member and the tool member is rotatablerelative to the second link about a second axis. A second guide path isdefined within the second link between the tool member and the firstguide path. The second link includes a curved guide surface that definesa portion of the second guide path. The curved guide surface ischaracterized by a radius about the first axis. The radius is equal tothe distance that the centerline of the first guide path is offset fromthe centerline of the shaft. The tension member has a first tensionmember portion, a second tension member portion, and a third tensionmember portion between the first tension member portion and the secondtension member portion. The first tension member portion is within thefirst guide path, and the second tension member portion is coupled tothe tool member. The third tension member portion is in contact with thecurved guide surface throughout at least a portion of the angular range.

In some embodiments, a low-friction medical device includes a firstlink, a second link, and a tension member. A first guide path is definedwithin the first link. A centerline of the first guide path is offsetfrom a centerline of the shaft by a first distance. The second link hasa proximal end portion and a distal end portion. The proximal endportion of the second link is rotatably coupled to the first link. Thesecond link is rotatable relative to the first link about a first axisthrough an angular range. The distal end portion of the second link isrotatably coupled to a tool member and the tool member is rotatablerelative to the second link about a second axis. A second guide path isdefined within the second link between the tool member and the firstguide path. The second link includes a curved guide surface that definesa portion of the second guide path. The curved guide surface ischaracterized by a radius of curvature. A center of the radius ofcurvature is offset from the centerline of the shaft by a seconddistance. The second distance is equal to the sum of the radius ofcurvature and the first distance. The tension member has a first tensionmember portion, a second tension member portion, and a third tensionmember portion between the first tension member portion and the secondtension member portion. The first tension member portion is within thefirst guide path, and the second tension member portion is coupled tothe tool member. The third tension member portion is in contact with thecurved guide surface throughout at least a portion of the angular range.

In some embodiments, the tool member has a pulley portion coupled to thedistal end portion of the second link by a pin. The second portion ofthe tension member is wrapped about the pulley portion offset from thepin such that the tool member rotates relative to the second link aboutthe second axis when the tension member is moved. The second portion ofthe tension member is parallel between the curved guide surface of thesecond link and the pulley portion of the tool member.

In some embodiments, a medical device includes a first link, a secondlink, and a tension member. The first link is coupled to an instrumentshaft and defines a first guide path. The second link is rotatablycoupled to the first link to rotate relative to the first link about afirst axis. The second link defines a second guide path, a retentionpocket, a connection path, and an assembly path. The connection pathextends through a portion of the second link between the second guidepath and the retention pocket. A wall of the second link surrounds aportion of the connection path. A connection path centerline and acenterline of the second guide path define a first plane within thesecond link. The assembly path extends through a portion of the secondlink into the retention pocket. A centerline of the assembly path isnonparallel to the connection path centerline within a second plane thatis nonparallel to the first plane. The tension member has a firsttension member portion, a second tension member portion, and a retentionmember coupled to the second tension member portion. The first tensionmember portion is configured to be: A) inserted through the assemblypath along the assembly path centerline, and B) rotated until the firsttension member portion is within the second guide path. The retentionmember is retained within the retention pocket after the first tensionmember portion is rotated such that movement of the tension memberrelative to the second link is limited. The second link is furtherconfigured to rotate relative to the first link about the first axiswhen the first tension member portion is moved within the second guidepath.

In some embodiments, the tension member is a cable and the retentionmember is a cable crimp. In some embodiments, the cable crimp isconfigured to have an angular twist from a relaxed state with respect toa longitudinal axis of the tension member at the cable crimp duringinstallation. In some embodiments, the first tension member portion isrotated through an installation angle of about ninety degrees. In someembodiments, an elongate slot is defined within the second link, and thecable crimp is configured to slide through the elongate slot and intothe retention pocket when the tension member portion is rotated. In someembodiments, the cable crimp is configured to return to the relaxedstate of no angular twist after installation. In some embodiments, asize of the retention pocket is greater than a size of the connectionpath. In some embodiments, the second plane is transverse to the firstplane. In some embodiments, the assembly path centerline and theconnection path centerline form an insertion angle of between 5 degreesand 45 degrees. In some embodiments, the retention member includes aswage connector attached to the tension member.

In some embodiments, a medical device includes a first link, a secondlink, and a tension member. The first link is coupled to an instrumentshaft and defines therein a first guide path. The second link isrotatably coupled a first link to rotate relative to the first linkabout a first axis. The second link defines a second guide path, aretention pocket, a connection path, and an assembly path. Theconnection path extends through a portion of the second link between thesecond guide path and the retention pocket. A first wall of the secondlink defining an elongate slot opening into the retention pocket. Asecond wall of the second link defines a distal boundary of theretention pocket. A connection path centerline and a centerline of thesecond guide path define a first plane within the second link. Theassembly path extends through the portion of the second link into theretention pocket. An assembly path centerline of the assembly path isnonparallel to the connection path centerline within a second plane thatis nonparallel to the first plane. The tension member has a firsttension member portion, a second tension member portion, and a retentionmember coupled to the second tension member portion. The first tensionmember portion is configured to be A) inserted through the elongate slotand the assembly path along the assembly path centerline, and B) rotateduntil the first tension member portion is within the second guide path.The retention member is retained within the retention pocket after thefirst tension member portion is rotated such that movement of thetension member relative to the second link is limited. The second linkis configured to rotate relative to the first link about the first axiswhen the first tension member portion is moved within the second guidepath.

In some embodiments, a method of assembling a portion of a wristassembly is provided, in which the wrist assembly includes a first linkand a second link. The first link defines a first guide path, and thesecond link is rotatably coupled to the first link to rotate relative tothe first link about a first axis. The method includes inserting a firstend portion of a tension member through an assembly path defined withinthe second link. The assembly path extends through a portion of thesecond link into a retention pocket defined by the second link. Thetension member includes a second end portion and a retention membercoupled to the second end portion. The method further includes rotating,after the inserting, a portion of the tension member about a rotationaxis that is nonparallel to a longitudinal axis of the first end portionof the tension member. The rotating causing the first end portion of thetension member to be within a second guide path and a connection pathdefined by the second link. The connection path extends through aportion of the second link between the second guide path and theretention pocket. An assembly path centerline of the assembly path isnonparallel to a connection path centerline of the connection path.

In some embodiments, the method of assembling a portion of a wristassembly further includes inserting the first end portion of the tensionmember into the first guide path. In some embodiments, the rotatingincludes rotating the tension member through an angle of between 5degrees and 45 degrees.

As used herein, the term “about” when used in connection with areferenced numeric indication means the referenced numeric indicationplus or minus up to 10 percent of that referenced numeric indication.For example, the language “about 50” covers the range of 45 to 55.Similarly, the language “about 5” covers the range of 4.5 to 5.5.

The term “flexible” in association with a part, such as a mechanicalstructure, component, or component assembly, should be broadlyconstrued. In essence, the term means the part can be repeatedly bentand restored to an original shape without harm to the part. Certainflexible components can also be resilient. For example, a component(e.g., a flexure) is said to be resilient if possesses the ability toabsorb energy when it is deformed elastically, and then release thestored energy upon unloading (i.e., returning to its original state).Many “rigid” objects have a slight inherent resilient “bendiness” due tomaterial properties, although such objects are not considered “flexible”as the term is used herein.

A flexible part may have infinite degrees of freedom (DOF's).Flexibility is an extensive property of the object being described, andthus is dependent upon the material from which the object is formed aswell as certain physical characteristics of the object (e.g.,cross-sectional shape, length, boundary conditions, etc.). For example,the flexibility of an object can be increased or decreased byselectively including in the object a material having a desired modulusof elasticity, flexural modulus and/or hardness. The modulus ofelasticity is an intensive property of (i.e., is intrinsic to) theconstituent material and describes an object's tendency to elastically(i.e., non-permanently) deform in response to an applied force. Amaterial having a high modulus of elasticity will not deflect as much asa material having a low modulus of elasticity in the presence of anequally applied stress. Thus, the flexibility of the object can bedecreased, for example, by introducing into the object and/orconstructing the object of a material having a relatively high modulusof elasticity. Examples of such parts include closed, bendable tubes(made from, e.g., NITINOL®, polymer, soft rubber, and the like), helicalcoil springs, etc. that can be bent into various simple or compoundcurves, often without significant cross-sectional deformation.

Other flexible parts may approximate such an infinite-DOF part by usinga series of closely spaced components that are similar to a serialarrangement of short, connected links as snake-like “vertebrae.” In sucha vertebral arrangement, each component is a short link in a kinematicchain, and movable mechanical constraints (e.g., pin hinge, cup andball, live hinge, and the like) between each link may allow one (e.g.,pitch) or two (e.g., pitch and yaw) DOFs of relative movement betweenthe links. A short, flexible part may serve as, and be modeled as, asingle mechanical constraint (a joint) that provides one or more DOF'sbetween two links in a kinematic chain, even though the flexible partitself may be a kinematic chain made of several coupled links havingmultiple DOFs, or an infinite-DOF link.

As used in this specification and the appended claims, the word “distal”refers to direction towards a work site, and the word “proximal” refersto a direction away from the work site. Thus, for example, the end of atool that is closest to the target tissue would be the distal end of thetool, and the end opposite the distal end (i.e., the end manipulated bythe user or coupled to the actuation shaft) would be the proximal end ofthe tool.

Further, specific words chosen to describe one or more embodiments andoptional elements or features are not intended to limit the invention.For example, spatially relative terms—such as “beneath”, “below”,“lower”, “above”, “upper”, “proximal”, “distal”, and the like—may beused to describe the relationship of one element or feature to anotherelement or feature as illustrated in the figures. These spatiallyrelative terms are intended to encompass different positions (i.e.,translational placements) and orientations (i.e., rotational placements)of a device in use or operation in addition to the position andorientation shown in the figures. For example, if a device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be “above” or “over” the other elementsor features. Thus, the term “below” can encompass both positions andorientations of above and below. A device may be otherwise oriented(e.g., rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors used herein interpreted accordingly. Likewise,descriptions of movement along (translation) and around (rotation)various axes includes various spatial device positions and orientations.The combination of a body's position and orientation define the body'spose.

Similarly, geometric terms, such as “parallel”, “perpendicular”,“round”, or “square”, are not intended to require absolute mathematicalprecision, unless the context indicates otherwise. Instead, suchgeometric terms allow for variations due to manufacturing or equivalentfunctions. For example, if an element is described as “round” or“generally round,” a component that is not precisely circular (e.g., onethat is slightly oblong or is a many-sided polygon) is still encompassedby this description.

In addition, the singular forms “a”, “an”, and “the” are intended toinclude the plural forms as well, unless the context indicatesotherwise. The terms “comprises”, “includes”, “has”, and the likespecify the presence of stated features, steps, operations, elements,components, etc. but do not preclude the presence or addition of one ormore other features, steps, operations, elements, components, or groups.

Unless indicated otherwise, the terms apparatus, medical device,instrument, and variants thereof, can be interchangeably used.

Aspects of the invention are described primarily in terms of animplementation using a da Vinci® Surgical System, commercialized byIntuitive Surgical, Inc. of Sunnyvale, Calif. Examples of such surgicalsystems are the da Vinci Xi® Surgical System (Model IS4000) and the daVinci Si® Surgical System (Model IS3000). Knowledgeable persons willunderstand, however, that inventive aspects disclosed herein may beembodied and implemented in various ways, including computer-assisted,non-computer-assisted, and hybrid combinations of manual andcomputer-assisted embodiments and implementations.

Implementations on da Vinci® Surgical Systems (e.g., the Model IS4000,the Model IS3000, the Model IS2000, the Model IS1200) are merelypresented as examples, and they are not to be considered as limiting thescope of the inventive aspects disclosed herein. As applicable,inventive aspects may be embodied and implemented in both relativelysmaller, hand-held, hand-operated devices and relatively larger systemsthat have additional mechanical support.

FIG. 1 is a plan view illustration of a computer-assisted teleoperationsystem. Shown is a medical device, which is a Minimally Invasive RoboticSurgical (MIRS) system 1000 (also referred to herein as a minimallyinvasive teleoperated surgery system), used for performing a minimallyinvasive diagnostic or surgical procedure on a Patient P who is lying onan Operating table 1010. The system can have any number of components,such as a user control unit 1100 for use by a surgeon or other skilledclinician S during the procedure. The MIRS system 1000 can furtherinclude a manipulator unit 1200 (popularly referred to as a surgicalrobot), and an optional auxiliary equipment unit 1150. The manipulatorunit 1200 can include an arm assembly 1300 and a tool assembly removablycoupled to the arm assembly. The manipulator unit 1200 can manipulate atleast one removably coupled instrument 1400 (also referred to as a“tool” or “tool assembly”) through a minimally invasive incision in thebody or natural orifice of the patient P while the surgeon S views thesurgical site and controls movement of the instrument 1400 throughcontrol unit 1100. An image of the surgical site is obtained by anendoscope (not shown), such as a stereoscopic endoscope, which can bemanipulated by the manipulator unit 1200 to orient the endoscope. Theauxiliary equipment unit 1150 can be used to process the images of thesurgical site for subsequent display to the Surgeon S through the usercontrol unit 1100. The number of instruments 1400 used at one time willgenerally depend on the diagnostic or surgical procedure and the spaceconstraints within the operating room, among other factors. If it isnecessary to change one or more of the instruments 1400 being usedduring a procedure, an assistant removes the instrument 1400 from themanipulator unit 1200 and replaces it with another instrument 1400 froma tray 1020 in the operating room. Although shown as being used with theinstruments 1400, any of the instruments described herein can be usedwith the MIRS 1000.

FIG. 2 is a perspective view of the control unit 1100. The user controlunit 1100 includes a left eye display 1112 and a right eye display 1114for presenting the surgeon S with a coordinated stereo view of thesurgical site that enables depth perception. The user control unit 1100further includes one or more input control devices 1116, which in turncause the manipulator unit 1200 (shown in FIG. 1) to manipulate one ormore tools. The input control devices 1116 provide at least the samedegrees of freedom as instruments 1400 with which they are associated toprovide the surgeon S with telepresence, or the perception that theinput control devices 1116 are integral with (or are directly connectedto) the instruments 1400. In this manner, the user control unit 1100provides the surgeon S with a strong sense of directly controlling theinstruments 1400. To this end, position, force, and tactile feedbacksensors (not shown) may be employed to transmit position, force, andtactile sensations from the instruments 1400 back to the surgeon's handsthrough the input control devices 1116.

The user control unit 1100 is shown in FIG. 1 as being in the same roomas the patient so that the surgeon S can directly monitor the procedure,be physically present if necessary, and speak to an assistant directlyrather than over the telephone or other communication medium. In otherembodiments however, the user control unit 1100 and the surgeon S can bein a different room, a completely different building, or other remotelocation from the patient allowing for remote surgical procedures.

FIG. 3 is a perspective view of the auxiliary equipment unit 1150. Theauxiliary equipment unit 1150 can be coupled with the endoscope (notshown) and can include one or more processors to process captured imagesfor subsequent display, such as via the user control unit 1100, or onanother suitable display located locally and/or remotely. For example,where a stereoscopic endoscope is used, the auxiliary equipment unit1150 can process the captured images to present the surgeon S withcoordinated stereo images of the surgical site via the left eye display1112 and the right eye display 1114. Such coordination can includealignment between the opposing images and can include adjusting thestereo working distance of the stereoscopic endoscope. As anotherexample, image processing can include the use of previously determinedcamera calibration parameters to compensate for imaging errors of theimage capture device, such as optical aberrations.

FIG. 4 shows a front perspective view of the manipulator unit 1200. Themanipulator unit 1200 includes the components (e.g., arms, linkages,motors, sensors, and the like) to provide for the manipulation of theinstruments 1400 and an imaging device (not shown), such as astereoscopic endoscope, used for the capture of images of the site ofthe procedure. Specifically, the instruments 1400 and the imaging devicecan be manipulated by teleoperated mechanisms having a number of joints.Moreover, the instruments 1400 and the imaging device are positioned andmanipulated through incisions or natural orifices in the patient P in amanner such that a kinematic remote center of motion is maintained atthe incision or orifice. In this manner, the incision size can beminimized.

FIGS. 5, 6A, 6B, and 7 are diagrammatic illustrations of variousportions of an instrument 2400, according to an embodiment. In someembodiments, the instrument 2400 or any of the components therein areoptionally parts of a surgical system that performs minimally invasivesurgical procedures and which can include a manipulator unit, a seriesof kinematic linkages, a series of cannulas, or the like. The instrument2400 (and any of the instruments described herein) can be used in anysuitable surgical system, such as the MIRS system 1000 shown anddescribed above. The instrument 2400 includes a wrist assembly 2500, atleast one tension member 2420, and a tool member 2462. Although only onetension member 2420 is shown, one or more additional tension members orone or more additional tool members can be included. As describedherein, the instrument 2400 is configured such that movement of thetension member 2420 produces movement of the wrist assembly 2500 (asshown in FIGS. 6A and 7), movement of the tool member 2462 (asillustrated in FIG. 5), or both movement of the wrist assembly 2500 andmovement of the tool member 2462.

The wrist assembly 2500 includes a proximal first link 2510 and a distalsecond link 2610. The first link 2510 has a proximal end portion 2511and a distal end portion 2512. The proximal end portion 2511 is coupledto an instrument shaft (not shown). Although the instrument shaft is notshown in FIGS. 5-7, the proximal end portion 2511 can be coupled to anysuitable instrument shaft, such as the instrument shaft 4410 (FIG. 9)shown and described herein. Moreover, the proximal end portion 2511 ofthe first link 2510 can be coupled to the instrument shaft via anysuitable mechanism, such as welding, interference fit, adhesive, etc. Asdescribed below, the distal end portion 2512 is rotatably coupled to thesecond link 2610. In this manner, the first link 2510 and the secondlink 2610 form the wrist assembly 2500 having a first axis of rotationA₁ (which functions as a pitch axis; the term pitch is arbitrary) aboutwhich the second link can rotate relative to the first link through anangular range of the wrist assembly. The proximal first link 2510defines a first guide path 2515 within and through the first link, whichextends from its proximal end portion 2511 to its distal end portion2512. At least a portion of the first guide path 2515 is parallel withthe centerline CL₁ of the shaft (not shown) but is offset from thecenterline of the shaft as discussed further below. As such, acenterline CL₂ of the first guide path 2515 is offset from thecenterline CL₁ of the shaft by a first distance d₁. In some embodiments,the centerline CL₁ of the shaft is coaxial with a centerline of thefirst link 2510 and intersects the first axis of rotation A₁. Thus, insuch embodiments the centerline CL₂ of the first guide path 2515 isoffset from the first axis of rotation A₁ of the shaft by a firstdistance d₁.

The second link 2610 has a proximal end portion 2611 and a distal endportion 2612. As described above, the proximal end portion 2611 isrotatably coupled to the distal end portion 2512 of the first link 2510to form a wrist joint. The axis of rotation A₁ is located on thecenterline CL₁ of the shaft (and in some embodiments, the first link2510) and along a centerline CL₃ of the second link 2610 (see FIG. 7).In a first orientation shown in FIGS. 5, 6A and 6B, the shaft centerlineCL₁ (also centerline of the first link 2510) and the centerline CL₃ ofthe second link are collinear. In a second orientation shown in FIG. 7,the shaft centerline CL₁ of the first link 2510 and the centerline CL₃of the second link form an angle (i.e., a pitch angle). In someembodiments, the proximal end portion 2611 can be coupled to the distalend portion 2512 via a pinned joint, such as the pinned joint betweenthe proximal clevis 220 and the distal clevis 230 shown and described inU.S. Pat. No. 8,821,480 B2 (filed Jul. 16, 2008), entitled “Four-CableWrist with Solid Surface Cable Channels,” which is incorporated hereinby reference in its entirety. In other embodiments the proximal endportion 2611 can be coupled to the distal end portion 2512 via matingdisc surfaces, such as the types shown and described in U.S. PatentApplication Pub. No. US 2017/0120457 A1 (filed Feb. 20, 2015), entitled“Mechanical Wrist Joints with Enhanced Range of Motion, and RelatedDevices and Methods,” which is incorporated herein by reference in itsentirety.

The distal end portion 2612 of the second link 2610 includes a connector2680 that is coupled to the tool member 2462 such that the tool member2462 can rotate relative to the wrist assembly 2500 about a second axisof rotation A₂ through an angular range. As shown in FIG. 5, the secondaxis of rotation A₂ (also referred to as the yaw axis or the grip axis)is non-parallel to the first axis of rotation A₁. As described herein,axis A₂ functions both as a yaw axis (the term yaw is arbitrary) as thetool member 2462 rotates together with another tool member (not shown,but a second tool member can optionally be included in the instrument2400) and as a grip axis as the tool member rotates in opposition toanother tool member (not shown). Thus, the instrument 2400 provides forup to three degrees of freedom (i.e., a pitch rotation about the firstaxis of rotation A₁, a yaw rotation about the second axis of rotationA₂, and a grip motion about the second axis of rotation A₂). Althoughthe second axis of rotation A₂ is shown as being normal to the firstaxis of rotation A₁, in other embodiments the second axis of rotation A₂can be offset from the first axis of rotation A₁ by any suitable angle.The connector can be any suitable connector to rotatably couple the toolmember 2462 to the second link 2610 to form a tool joint. For example,in some embodiments, the connector 2680 can include a clevis and a pin,such as the pinned joints shown and described in U.S. Pat. No. 9,204,923(filed Jul. 16, 2008), entitled “Medical Instrument ElectronicallyEnergized Using Drive Cables,” which is incorporated herein by referencein its entirety. In other embodiments the connector 2680 can include acompliant mechanism, such as the compliant mechanisms shown anddescribed in International Publication No. WO 2016/123139 A2 (filed Jan.26, 2016), entitled “Rolling-Contact Joint Mechanisms and Methods,”which is incorporated herein by reference in its entirety.

The second link 2610 defines a second guide path 2615 within and throughthe second link, which extends from the first guide path 2515 at itsproximal end portion 2611 to the tool member 2462 at its distal endportion 2612. The second link includes an inner guide surface 2616 thatdefines a portion of the second guide path, and is located on an innerportion of the second guide path 2615 with respect to the second link2610. Although the inner guide surface 2616 is shown as being locatedalong the second guide path 2615 at the proximal end portion 2611 of thesecond link 2610, in other embodiments the inner guide surface 2616 canbe at any suitable location of or define any suitable portion of thesecond guide path 2615. The inner guide surface 2616 is curved withrespect to the first axis of rotation A₁ such that the inner guidesurface has a radius of curvature R_(bend) from the first axis ofrotation A₁ that extends throughout the angular range of rotation of thewrist assembly 2500 about the first axis of rotation A₁ in the directionCC shown in FIGS. 6A and 7. Although the radius of curvature R_(bend) isshown as being centered at the first axis of rotation A₁, in otherembodiments the radius of curvature of the inner guide surface 2616 canbe centered at any suitable location. As discussed further below, theinner guide surface 2616 and the radius of curvature R_(bend) areconfigured to maintain a portion of the tension member 2420 locatedwithin the first guide path 2515 to be centered therein to reducefrictional contact of the tension member 2420 during movement of thesecond link 2610 with respect to the first link 2510, movement of thetool member 2462 with respect to the second link 2610, or both movementof the tool member 2462 and the second link 2610.

The second link further includes an outer guide surface 2619 thatdefines a portion of the second guide path 2615 and is located on anouter portion of the second guide path 2615 with respect to the secondlink 2610. Although the outer guide surface 2619 is shown as beinglocated within the second guide path 2615 near the distal end portion2612, in other embodiments the outer guide surface 2619 can be at anysuitable location of, or define any suitable portion of, the secondguide path 2615. As discussed further below, the outer guide surface2619 biases the tension member 2420 into contact with the inner guidesurface 2616. In addition, the distal outer guide surface is configuredto align the tension member 2420 with the tool member 2462 forattachment thereto.

The tension member 2420 has a proximal end portion 2421, a distal endportion 2422 coupled to the tool member 2462, a distal central portion2423, and a proximal central portion 2425. The proximal end portion 2421is located within a portion of the first guide path 2515 of the firstlink 2510. The distal central portion 2423 is between the distal endportion and proximal central portion 2425 and is located within thesecond guide path 2615 of the second link 2610. The proximal centralportion 2425 is between the distal central portion 2423 and the proximalend portion 2421. At least the inner guide surface 2616 of the secondlink 2610 contacts the distal central portion 2423 of the tension member2420 when the second link 2610 is in the first orientation shown inFIGS. 5, 6A, and 6B. Similarly stated, the distal central portion 2423of the tension member 2420 is in contact with the inner guide surface2616 throughout a portion of the angular range of motion of the secondlink 2610 relative to the first link 2510. The inner guide surface 2616guides the path of the tension member 2420 to transition within thesecond curved guide path 2615 while in the first orientation shown inFIG. 6A and also when the second link 2610 rotates relative to the firstlink 2510 in direction CC as shown. Specifically, the inner guidesurface 2616 is sized and positioned such that the proximal end portion2421, the proximal central portion 2425, or both the proximal endportion 2421 and the proximal central portion 2425 of the tension memberare alignment with the centerline CL₂ of the first guide path 2515.Similarly stated, this arrangement causes the proximal end portion 2421,the proximal central portion 2425, or both the proximal end portion 2421and the proximal central portion 2425 of the tension member to beparallel to the centerline CL₂. Moreover, the radius of curvatureR_(bend) of the inner guide surface 2616 is positioned and sized suchthat the proximal end portion 2421, the proximal central portion 2425,or both the proximal end portion 2421 and the proximal central portion2425 of the tension member remain parallel to the centerline CL₂ for therange of motion of the second link 2610 with respect to the first link2510 in the direction CC. As such, the tension member 2420 can movewithin the first guide path 2515 in the directions shown by arrow ABwithout contacting surfaces within the first guide path. In this manner,frictional contact is reduced for movements of the tension member 2420for the angular range of motion in direction CC.

In some embodiments, the inner guide surface 2616 has a radius ofcurvature R_(bend) about the first axis of rotation A₁ that is less thanor equal to the distance d₁ such that the proximal end portion 2421, theproximal central portion 2425, or both the proximal end portion 2421 andthe proximal central portion 2425 of the tension member remain parallelto the centerline CL₂ over the range of motion of the second link 2610.Although shown as being a single radius of curvature R_(bend), in otherembodiments the inner guide surface 2616 can be a curved surface that ischaracterized by multiple different radii of curvature.

As described below along with other embodiments herein, in someembodiments a second tension member (not shown) can be similarly offsetin an opposite direction from the longitudinal centerline CL₁ of thefirst link 2510 and the first axis A₁ to impart rotation in directionCC.

The proximal end portion 2421 of the tension member 2420 extendsproximally out of the wrist assembly 2500, through the instrument shaft(not shown), and is coupled to an actuator (not shown) at the proximalend of the instrument. The actuator (which functions as a transmission)can move the proximal end portion 2421 of the cable by any suitablemechanism to produce a resulting movement (or force) at the distal endportion 2422 of the cable (as shown by arrow AB in FIGS. 5 and 6A). Insome embodiments the actuator of the instrument 2400 is motor driven andis thus suitable for a robotic or teleoperated surgical system. Theproximal central portion 2425 and the distal central portion 2423 of thetension member 2420 are disposed within the second guide path 2615, andthe distal end portion 2422 of the cable is coupled to the tool member2462. In this manner, as described herein, movement of the tensionmember 2420 can produce rotation of the tool member 2462, rotation ofthe second link 2610, or rotation of both the tool member 2462 and thesecond link 2610. The distal end portion 2422 of the tension member 2420(e.g., a cable) can be coupled to the tool member 2462 by any suitablemechanism. For example, in some embodiments, the distal end portion 2422can be coupled to the tool member 2462 by a pin or protrusion thatengages (or is received within) a connection portion of the tool member2462. In other embodiments the distal end portion 2422 can be coupled tothe tool member 2462 via an adhesive. In yet other embodiments thedistal end portion 2422 of the tension member can be wrapped about apulley portion of the tool member 2462.

Referring to FIG. 5, the tool member 2462 is coupled to the wristassembly 2500 and rotates relative to the wrist assembly around thesecond axis of rotation A₂. Specifically, the first and second guidepaths 2510, 2615 are offset from the second axis of rotation A₂ by adistance d₂. In this manner, application of a tension force on thetension member 2420 in the proximal direction (indicated as direction Bby the arrow AB) produces a torque on the tool member 2462 about thesecond axis of rotation A₂, which results in rotation of the tool member2462 relative to the second link 2610, as shown by the arrow DD in FIG.5. In this manner, a distal portion (e.g., an engagement portion) of thetool member 2462 can engage or manipulate a target tissue during asurgical procedure. The tool member 2462 (or any of the tool membersdescribed herein) can be any suitable medical tool member. For example,in some embodiments the tool member 2462 (or any of the tool membersdescribed herein) can include an engagement surface that functions as agripper, cutter, tissue manipulator, or the like. In other embodimentsthe tool member 2462 (or any of the tool members described herein) canbe an energized tool member that is used for cauterization procedures.Although only one tool member 2462 is shown, in other embodiments theinstrument 2400 includes two moving tool members that cooperativelyperform gripping or shearing functions. In this manner, the tool member2462 can form a portion of an end effector for the surgical instrument2400.

As shown in FIG. 7, the second link 2610 defines a longitudinalcenterline CL₃ that intersects the first axis of rotation A₁. When thewrist assembly 2500 is in the first orientation (FIGS. 5, 6A and 6B),the longitudinal centerline CL₁ of the first link 2510 and thelongitudinal centerline CL₃ of the second link 2610 are collinear (andare collectively identified as CL₁ in FIG. 5). When the second link 2610rotates relative to the first link 2510 (i.e., rotates in pitch), thelongitudinal centerline CL₁ of the first link 2510 and the longitudinalcenterline CL₃ of the second link form a pitch angle. Throughout theangular range of motion in direction CC, including at the high pitchangle shown in FIG. 7, the tension member 2420 is maintained inalignment with the centerline CL₂ of the first guide path 2515 withoutfrictional contact with surfaces of the first link 2510 within the firstguide path.

Referring again to FIG. 7, the reduced amount of frictional contactbetween the tension member 2420 and components of the wrist assembly2500 when the instrument is in a high pitch orientation allows thetension member 2420 to be moved in the direction AA to move the toolmember 2462 when in a high pitch orientation in an efficient manner andwith a reduced likelihood that the tension member 2420 will becomebound. This allows movement of the tool member 2462 throughout the rangeof pitch orientations (e.g., at pitch angles of between zero degrees(FIG. 6A) and 90 degrees (FIG. 7), at pitch angles of between zerodegrees and 45 degrees, at pitch angles of between zero degrees and 60degrees).

In some embodiments, the tension member 2420 (and any of the tensionmembers described herein) can be formed as a cable made of Tungsten orstainless steel to provide sufficient strength, bendability anddurability. In some embodiments, cables can be constructed from multiplebraids of fine wire, to provide strength and resiliency. In someembodiments, cables can be made from 150 to 350 braids of 0.018 mm to0.025 mm (0.0007-inch to 0.001-inch) diameter tungsten wire providingcables with outer diameters of 0.356 mm to 0457 mm (0.014 inches to0.018 inches).

In some embodiments, the instrument 2400 can include any suitabletension member. For example, in some embodiments, the instrument 2400(and any of the instruments described herein) can include a tensionmember having any suitable cross-sectional shape. For example, in someembodiments the instrument 2400 (and any of the instruments describedherein) can include a tension band, of the types shown and described inU.S. Patent Application No. 62/598,620 (filed Dec. 14, 2017), entitled“Medical Tools Having Tension Bands,” which is incorporated herein byreference in its entirety. In some embodiments, such bands (and any ofthe tension members described herein) can have a trapezoidal shape. Inother embodiments such bands (and any of the tension members describedherein) can include slightly curved surfaces. Moreover, such bands (andany of the tension members described herein) can be constructed from anysuitable materials. For example, in some embodiments, such bands (andany of the tension members described herein) can be constructed from aseries of laminates that are bonded together (e.g., via an adhesive).The laminates can be constructed from any suitable material, includingtungsten, steel, or any suitable polymer.

Although the first link 2510 and the second link 2610 are shown ashaving a rectangular cross-sectional shape, in other embodiments eitherthe first link 2510, the second link 2610, or both the first link 2510and the second link 2610 can have any suitable cross-sectional shape.For example, in some embodiment, either the first link 2510, the secondlink 2610, or both the first link 2510 and the second link 2610 can havesubstantially circular cross-sectional shape (i.e., the wrist assembly2500 can be substantially cylindrical).

Although the second link 2610 is shown and described as having an innerguide surface 2616 (i.e., a surface located on an inner portion of thesecond guide path 2615), in other embodiments the second link 2610 canhave a curved surface in any suitable location within (or that definesany portion of) the second guide path 2615. For example, in someembodiments, the second link 2610 can include a curved surface locatedon an outer portion of the second guide path (i.e., an outer guidesurface) that contacts a portion of the tension member 2420 such thatthe proximal end portion 2421, the proximal central portion 2425, orboth the proximal end portion 2421 and the proximal central portion 2425of the tension member remain parallel to the centerline CL₂.

In some embodiments, the inner guide surface 2616 (or any of thesurfaces within the second guide path 2615 or the first guide path 2515)can be coated, treated or otherwise produced to have a low-frictionsurface. For example, in some embodiments, the inner guide surface 2616(or any of the surfaces within the second guide path 2615 or the firstguide path 2515) can be characterized by a coefficient of friction ofless than 0.1. In some embodiments, the inner guide surface 2616 (or anyof the surfaces within the second guide path 2615 or the first guidepath 2515) can be coated with a friction-reducing composition, such as anitride coating.

In some embodiments, the first link 2510, the second link 2610, or anyof the links described herein can include rollers, bearings, or otherfriction-reducing mechanism within the first guide path 2515, the secondguide path 2615, or any of the guide paths described herein. Forexample, in some embodiments, the inner guide surface 2616 can be anouter surface of a pulley coupled to the second link 2610. In otherembodiments the first link 2510, the second link 2610, or any of thelinks described herein can include rollers of the types shown anddescribed in the U.S. Provisional Patent Application bearing docketnumber ISRG10440PROV/US (filed on the same date as this application),entitled “Low-Friction Medical Tools Having Roller-Assisted TensionMembers,” which is incorporated herein by reference in its entirety.

Although the instrument 2400 is shown and described as including asingle tool member 2462 and a single tension member (i.e., the tensionmember 2420), in other embodiments an instrument can include anysuitable number of tension members or tool member. For example, in someembodiments, an instrument can include four tension members (or portionsof tension members). FIG. 8A is a schematic illustration of a portion ofan instrument 3400, according to an embodiment. The instrument 3400includes a wrist assembly 3500, a first tension member 3420, a secondtension member 3440, and an end effector 3460. The instrument 3400 isconfigured such that movement of various portions of the first tensionmember 3420 and the second tension member 3440 can produce movement ofthe wrist assembly 3500 about the pitch axis A₁, movement of the endeffector 3460 about the yaw axis A₂, gripping motion of the end effector3460, or any combination of these motions.

The wrist assembly 3500 (which functions as a joint assembly) includes afirst link 3510 and a second link 3610. The first link 3510 is coupledto an instrument shaft (not shown) of the types shown and describedherein. The second link 3610 has a proximal end portion and a distal endportion. The proximal end portion is rotatably coupled to the first link3510 to form the wrist assembly 3500 having a first axis of rotation A₁(which functions as the pitch axis, the term pitch is arbitrary) aboutwhich the second link 3610 can rotate relative to the first link 3510.The wrist assembly 3500 can include any suitable coupling mechanism. Forexample, in some embodiments, the second link 3610 can be coupled to thefirst link 3510 via a pinned joint of the types shown and describedherein. In other embodiments the second link 3610 can be coupled to thefirst link 3510 via mating disc surfaces of the types shown anddescribed herein.

The distal end portion of the second link 3610 is coupled to the endeffector 3460. More specifically, the distal end portion of the secondlink 3610 is coupled to a pulley portion 3467 of a first tool member3462 and a pulley portion 3487 of a second tool member 3482. Thisarrangement allows each of the tool member 3462 and the tool member 3482to rotate relative to the wrist assembly 3500 about a second axis ofrotation A₂. The second axis of rotation A₂ is non-parallel to the firstaxis of rotation A₁ and functions both as a yaw axis (the term yaw isarbitrary) as tool members rotate together and as a grip axis as toolmembers rotate in opposition to each other. Thus, the instrument 3400provides for up to three degrees of freedom (i.e., a pitch motion aboutthe first axis of rotation A₁, a yaw rotation about the second axis ofrotation A₂, and a grip motion about the second axis of rotation A₂).Although the end effector 3460 is shown as being coupled to the secondlink 3610 via a pin connector, in other embodiments the end effector3460 can be coupled to the wrist assembly 3500 by any suitablemechanism.

The end effector includes the first tool member 3462 and the second toolmember 3482. The first tool member 3462 includes a contact portion 3464and a pulley portion 3467, and the second tool member 3482 includes acontact portion 3484 and a pulley portion 3487. The contact portion 3464and the contact portion 3484 are each configured to engage or manipulatea target tissue during a surgical procedure. For example, in someembodiments, the contact portions can include an engagement surfacesthat function as a gripper, cutter, tissue manipulator, or the like. Inother embodiments the contact portions can be an energized tool memberthat is used for cauterization procedures. As described above, thepulley portion 3467 and the pulley portion 3487 are each rotatablycoupled to the second link 3610 such that the tool member 3462 canrotate relative to the wrist assembly 3500 via the second axis ofrotation A₂. The pulley portions can include a contact surface aboutwhich the corresponding tension members (i.e., the first tension member3420 and the second tension member 3440) are wrapped. The first toolmember 3462 and the second tool member 3482 (or any of the tool membersdescribed herein) can be any suitable tool member of the types shown anddescribed herein.

The first tension member 3420 (which can be a band or a cable) has afirst proximal end portion 3421, a second proximal end portion 3431, anda distal end portion 3422. As shown, the distal end portion 3422 iswrapped about the pulley portion 3467 of the first tool member 3462. Inthis manner, the first proximal end portion 3421 and the second proximalend portion 3431 each extend through the first link 3510 and into theinstrument shaft (not shown). Additionally, the first proximal endportion 3421 and the second proximal end portion 3431 are each coupledto an actuator (not shown) that can move each of the proximal endportions (as shown by the series of arrows labeled as PITCH, YAW, andGRIP). A first distal guide post 3617 is attached to the second link3610 adjacent to a first intermediate portion 3423 of the first tensionmember 3420 that extends between the first proximal end portion 3421 andthe distal end portion 3422 of the first tension member when the wristassembly 3500 is in a first orientation shown in FIG. 8A. An outersurface of the first distal guide post 3617 contacts the firstintermediate portion 3423 of the first tension member 3420 when thewrist assembly 3500 is in the first orientation. A first proximal guidepost 3522 is attached to the first link 3510 adjacent to a secondintermediate portion 3433 of the first tension member 3420 that extendsbetween the second proximal end portion 3431 and the distal end portion3422 of the first tension member when the wrist assembly 3500 is in thefirst orientation shown in FIG. 8A. An outer surface of the firstproximal guide post 3522 contacts the second intermediate portion 3433of the first tension member 3420 when the wrist assembly 3500 is in thefirst orientation.

The second tension member 3440 (which can be a band or a cable) has athird proximal end portion 3441, a fourth proximal end portion 3451, anda distal end portion 3442. As shown, the distal end portion 3442 iswrapped about the pulley portion 3487 of the second tool member 3482. Inthis manner, the third proximal end portion 3441 and the fourth proximalend portion 3451 each extend through the first link 3510 and into theinstrument shaft (not shown). Additionally, the third proximal endportion 3441 and the fourth proximal end portion 3451 are each coupledto an actuator (not shown) that can move each of the proximal endportions (as shown by the series of arrows labeled as PITCH, YAW, andGRIP). A second proximal guide post 3532 is attached to the first link3510 adjacent to a fourth intermediate portion 3443 of the secondtension member 3440 that extends between the fourth proximal end portion3451 and the distal end portion 3442 of the second tension member whenthe wrist assembly 3500 is in the first orientation shown in FIG. 8A. Anouter surface of the second proximal guide post 3532 contacts the fourthintermediate portion 3443 of the second tension member 3440 when thewrist assembly 3500 is in the first orientation. A second distal guidepost 3627 is attached to the second link 3610 adjacent to a thirdintermediate portion 3453 of the second tension member 3440 that extendsbetween the third proximal end portion 3441 and the distal end portion3442 of the second tension member when the wrist assembly 3500 is in afirst orientation shown in FIG. 8A. An outer surface of the seconddistal guide post 3627 contacts the third intermediate portion 3453 ofthe second tension member 3440 when the wrist assembly 3500 is in thefirst orientation.

In some embodiments, the first tension member 3420 or the second tensionmember 3440 (or both) can be monolithically constructed such that thefirst proximal end portion, the second proximal end portion, and thedistal end portion are all within a single element. In other embodimentshowever, the first tension member 3420 or the second tension member 3440(or both) can include multiple separately constructed components (e.g.,the first proximal end portion 3421 can be separately constructed fromthe second proximal end portion 3431). Moreover, the first tensionmember 3420 or the second tension member 3440 (or both) can have anysuitable shape as described herein. In some embodiments, the firsttension member 3420 or the second tension member 3440 (or both) can havevarying cross-sectional areas. In some embodiments, the first tensionmember 3420 or the second tension member 3440 (or both) can beconstructed from a series of laminates that are bonded together (e.g.,via an adhesive). The laminates can be constructed from any suitablematerial, including tungsten, steel, or any suitable polymer. In someembodiments, the first tension member 3420 and the second tension member3440 can be constructed as steel cables.

Changing the pitch, yaw, or grip of the instrument 3400 generallyrequires movements or actions respectively applied to each of the fourproximal end portions (the first proximal end portion 3421, the secondproximal end portion 3431, the third proximal end portion 3441, and thefourth proximal end portion 3451). The movement of the tension memberportions can generally be performed one at a time or simultaneously inany desired combination to change the pitch, yaw, and grip of instrument3400. For example, pitch axis rotations rotate the second link 3610about the first axis of rotation A₁ (pitch axis), as shown by the arrowMM. For clockwise rotation about the pitch axis A₁, the actuators (notshown) pull in (i.e., move proximally) identical lengths of the firstproximal end portion 3421 and the second proximal end portion 3431 whilereleasing (i.e., allowing to move distally) the same lengths of thethird proximal end portion 3441 and the fourth proximal end portion3451. This is illustrated by the arrows labeled as PITCH.

The first proximal end portion 3421 and the second proximal end portion3431 apply forces to the second link 3610 at moment arms defined by thecurved guide paths through the wrist assembly 3500. Similarly stated,the first link 3510 and the second link 3610 can define one or morecurved guide paths that are offset from the pitch axis A₁ to produce atorque about the pitch axis A₁. The curved guide paths can be any of thecurved guide paths described herein (e.g., the curved guide paths shownand described in connection with the wrist assembly 2500 or the wristassembly 4500). Similarly, for counterclockwise rotation of the secondlink 3610 about the pitch axis A₁, the actuators pull in (i.e., moveproximally) identical lengths of the third proximal end portion 3441 andthe fourth proximal end portion 3451 while releasing (i.e., allowing tomove distally) the same lengths of the first proximal end portion 3421and the second proximal end portion 3431.

Yaw rotations are the rotation of the first tool member 3462 and thesecond tool member 3482 about the second axis of rotation A₂ (yaw axis)in the same direction and through the same angle. In particular, whenthe actuators pull in (i.e., move proximally) a length of the firstproximal end portion 3421 and release (i.e., allow to move distally) anequal length of the second proximal end portion 3431, the first toolmember 3462 will rotate in a clockwise direction about the yaw axis A₂(see the arrow NN). For this rotation, the curved guide path or pulleysurface of the pulley portion 3467 defines the moment arm at which forcetransmitted via the first tension member 3420 is applied. The resultingtorque causes the first tool member 3462 to rotate clockwise. Duringthis movement, the first proximal end portion 3421 and the secondproximal end portion 3431 each slide within the curved guide paths ofthe second link 3610. If, at the same time, the actuators pull in alength of the fourth proximal end portion 3451 and release the samelength of the third proximal end portion 3441, the second tool member3482 will rotate clockwise through an angle that is the same as theangle through which the first tool member 3462 rotates. Accordingly, thefirst tool member 3462 and the second tool member 3482 maintain theirpositions relative to each other and rotate as a unit through a yawangle. Counterclockwise rotation of the end effector 3460 is similarlyaccomplished when the actuators pull in equal lengths of the secondproximal end portion 3431 and the third proximal end portion 3441 whilereleasing the same lengths of the first proximal end portion 3421 andthe fourth proximal end portion 3451. This is illustrated by the arrowslabeled as YAW.

Grip rotations are rotations of the first tool member 3462 and thesecond tool member 3482 about the yaw axis A₂ in opposite directions andthrough the same angle. To open the grip of the end effector 3460, theactuators pull in equal lengths of the first proximal end portion 3421and the third proximal end portion 3441 while releasing the same lengthsof the second proximal end portion 3431 and the fourth proximal endportion 3451. This causes the first tool member 3562 to rotate in anopposite direction from the second tool member 3482. To close the gripof the end effector, the actuators pull in equal lengths of the secondproximal end portion 3431 and the fourth proximal end portion 3451 whilereleasing the same lengths of the first proximal end portion 3421 andthe third proximal end portion 3441. This causes the first tool member3562 to rotate towards the second tool member 3482. When contact portionof the tool members come into contact, the tension in the secondproximal end portion 3431 and the fourth proximal end portion 3451 canbe kept greater than the tension in the first proximal end portion 3421and the third proximal end portion 3441 to maintain the desired grippingforces.

The proximal guide posts (first proximal guide post 3522 and secondproximal guide post 3532) are each coupled to the first link 3510 onopposite sides of the pitch axis A₁ between the first tension member3420 and the second tension member 3440. The outer surface of the firstproximal guide post 3522 contacts the second intermediate portion 3433of the first tension member while in the orientation shown in FIG. 8A.Likewise, the outer surface of the second proximal guide post 3532contacts the fourth intermediate portion 3443 of the second tensionmember while in the orientation shown in FIG. 8A. As such, the outersurfaces of the proximal guide posts 3522, 3532 guide the position andorientation of the first tension member 3420 and the second tensionmember 3440 as the tension members move. As such, the proximal guideposts 3522, 3532 maintain the inner intermediate portions (secondintermediate portion 3433 and fourth intermediate portion 3443) of thefirst and second tension members 3420, 3440 in parallel alignment withthe instrument shaft regardless of the pitch, yaw and grip movements ofthe wrist assembly 3500. Maintaining this parallel alignment preventsinterfering contact between the first and second tension members 3420,3440 and other objects from occurring during movements of the wristassembly that can cause the tension members to bind or become entangled.In addition, maintaining this parallel alignment reduces friction duringoperations of the wrist assembly 3500 by avoiding rubbing or otherfrictional contact from occurring between the first and second tensionmembers 3420, 3440 and other portions of the wrist assembly 3500 and itscomponents.

Further, first and second proximal guide posts 3522, 3532 advantageouslyreduce friction at high tensile stress positions along the tensionmembers 3420, 3440. In particular, each of the first and second proximalguide posts 3522, 3532 is located on the first link 3510 on oppositesides of the pitch pivot A₁, about which second link 3610 rotates forpitch movements. When high pitch movements are made, high tensilestresses are applied to the first and second tension members 3420, 3440located on the side opposite the direction of pitch rotation. The firstand second proximal guide posts 3522, 3532 can reduce friction at thehigh tensile stress locations proximate the pitch pivot A1, which canreduce wear on the first and second tension members 3420, 3440 andenhance operation of the wrist assembly 3500.

The distal guide posts (first distal guide post 3617 and second distalguide post 3627) are each coupled to the second link 3610 on opposite,outer portions of the second link 3610. The outer surface of the firstdistal guide post 3617 contacts the first intermediate portion 3423 ofthe first tension member while in the orientation shown in FIG. 8A.Likewise, the outer surface of the second distal guide post 3627contacts the third intermediate portion 3453 of the second tensionmember while in the orientation shown in FIG. 8A. As such, the outersurface of each of the distal guide posts 3617, 3627 guide the positionand orientation of the first tension member 3420 and the second tensionmember 3440. The distal guide posts 3617, 3627 are coupled to the secondlink 3610 that rotates during pitch movements of the wrist assembly3500. As such, the distal guide posts 3617, 3627 guide the outerintermediate portions (third intermediate portion 3453 and firstintermediate portion 3423) of the first and second tension members 3420,3440 during pitch rotation movements to keep the first and secondtension members 3420, 3440 properly positioned to avoid them catching onobjects during movements of the wrist assembly and binding or becomingtangled. Further, distal guide posts 3617, 3627 advantageously guide thepaths of the first and second tension members 3420, 3440 throughout therange of motion for pitch movements with low friction.

The first and second proximal guide posts 3522, 3532 and the first andsecond distal guide posts 3617, 3627 can be any suitable guide post ofthe types shown and described herein. For example, in some embodiments,any of the first and second proximal guide posts 3522, 3532 and thefirst and second distal guide posts 3617, 3627 can have a radius that isless than a radius of curvature of any of the guide paths defined withinthe wrist assembly 3500. Moreover, although the first and secondproximal guide posts 3522, 3532 and the first and second distal guideposts, 3617, 3627 are shown and described as being in contact with theirrespective portions of the first tension member 3420 and the secondtension member 3440, when the wrist assembly is in a secondconfiguration, any of the first and second proximal guide posts 3522,3532 and the first and second distal guide posts 3617, 3627 can bespaced apart from their respective portions of the first tension member3420 and the second tension member 3440.

The wrist assembly 3500 (and any of the wrist assemblies describedherein) can include any suitable structure to define any suitable guidepaths within which the tension members move including using multipleguide posts to maintain the proximal end portions of the tension membersin parallel alignment with their connections in the shaft throughoutvarious movements of the wrist assembly. For example, referring to FIG.8B, in some embodiments, a first link 3510′ includes pairs of inner andouter guide posts that together maintain the proximal end portions ofeach tension member in parallel alignment with the shaft, which canavoid frictional contact of the tension members with portions of thewrist assembly during movements.

A first pair of guide posts includes a first inner guide post 3516′ anda first outer guide post 3517′ located along the first intermediateportion 3423′ of the first tension member 3420′ between the firstproximal end portion 3421′ and the second proximal end portion 3431′.The first inner guide post 3516′ is located on an inner side of thefirst intermediate portion 3423′ and first outer guide post 3517′ islocated on an outer side of the first intermediate portion 3423′. In asimilar manner, a second pair of guide posts includes a second innerguide post 3521′ located on an inner side of the second intermediateportion 3433′ of the first tension member 3420′, and a second outerguide post 3522′ located on an outer side of the second intermediateportion 3433′. Further, a third pair of guide posts includes a thirdinner guide post 3526′ located on an inner side of the thirdintermediate portion 3453′ of the second tension member 3440′, and thirdouter guide post 3527′ located on an outer side of the thirdintermediate portion 3453′. Likewise, a fourth pair of guide postsincludes a fourth inner guide post 3531′ located on an inner side of thefourth intermediate portion 3443′ of the second tension member 3420′,and a fourth outer guide post 3532′ located on an outer side of thefourth intermediate portion 3443′.

The guide posts of each of the pairs are co-located along acorresponding intermediate portion of the tension members such that eachpair forms a goal-post type guide along, and on each side of, thecorresponding intermediate portion (3423′, 3433′, 3443′, 3453′) thatmaintains the corresponding first tension member portion (3421′, 3431′,3441′, and 3451′) in parallel alignment with the corresponding actuator(not shown). The guide post pairs maintain this parallel alignment whilethe wrist assembly 3500′ is in the first orientation shown in FIG. 8Band in other orientations, as well as during movements of the wristassembly 3500′. Each of the inner guide posts (3516′, 3521′, 3526′ and3531′) in each of the pairs can be spaced apart from the correspondingouter guide post (3517′, 3522′, 3527′ and 3532′) such that thecorresponding intermediate portion (3523′, 3233′, 3443′ and 3553′)disposed therebetween does not contact the guide posts while in thefirst orientation shown in FIG. 8B and, thus, can move freely in thelongitudinal direction of the tension member 3220′ and 3420′ withoutfrictional contact with the guide posts. As such, the tension members3420′ and 3440′ can move longitudinally in-line with their longitudinalaxis while in the first orientation with reduced friction. Further, whenthe second link 3610′ rotates with respect to the first link 3510′ aboutthe first axis A₁′, the pairs of guide posts can maintain the portionsof the first and second tension members 3420′ and 3440′ disposed betweenthe pairs of guide posts and the corresponding actuator (not shown) inparallel alignment with the corresponding actuator, which can avoidfrictional contact with portions of the wrist assembly 3500 and reducethe likelihood of the tension members binding.

FIGS. 9-17 are various views of an instrument 4400, according to anembodiment. In some embodiments, the instrument 4400 or any of thecomponents therein are optionally parts of a surgical assembly thatperforms minimally invasive surgical procedures, and which can include amanipulator unit, a series of kinematic linkages, a series of cannulas,or the like. The instrument 4400 (and any of the instruments describedherein) can be used in any suitable surgical system, such as the MIRSsystem 1000 shown and described above. The instrument 4400 includes atransmission mechanism 4700 (e.g., transmission assembly) (that canfunction as an actuator mechanism), an instrument shaft 4410, a wristassembly 4500, and an end effector 4460.

Referring to FIG. 10, the instrument 4400 also includes a first tensionmember 4420 and a second tension member 4440 that couple thetransmission mechanism 4700 to the wrist assembly 4500. The instrument4400 is configured such that movement of the tension members can producerotation of the wrist assembly 4500 (i.e., pitch rotation) about a firstaxis of rotation A₁, yaw rotation of the end effector 4460 about asecond axis of rotation A₂, grip rotation of the tool members of the endeffector 4460 about the yaw axis, or any combination of these movements.Changing the pitch, yaw, or grip of the instrument 4400 can be performedby manipulating the four tension members in similar manner as thatdescribed above for the instrument 3400. Thus, the specific movement ofeach of the four tension members to accomplish the desired motion is notdescribed below. Although shown and described as including two tensionmembers that are wrapped about the end effector 4460 resulting in fourproximal end tension member portions (i.e., the four-tension memberarrangement), in other embodiments the instrument 4400 can includeadditional tension members that separately change the pitch of theinstrument 4400.

The transmission mechanism 4700 produces movement of each of the firsttension member 4420 and the second tension member to produce the desiredmovement (pitch, yaw, or grip) at the wrist assembly 4500. Specifically,the transmission mechanism 4700 includes components and controls to movesome of the tension members in a proximal direction (i.e., to pull incertain tension members) while simultaneously allowing the distalmovement (i.e., releasing or “paying out”) of other of the tensionmembers in equal lengths. In this manner, the transmission mechanism4700 can maintain the desired tension within the tension members, andcan ensure that the lengths of the tension members are conserved (i.e.,moved in equal amounts) during the entire range of motion of the wristassembly 4500. In some embodiments, for example, the transmissionmechanism 4700 can be any of the transmission assemblies shown anddescribed in International Patent Application No. PCT/US2017/062258,(filed Nov. 14, 2017), entitled “Cable Length Conserving MedicalInstrument,” which is incorporated herein by reference in its entirety.In other embodiments however, conservation of the lengths of the tensionmembers is not required.

In some embodiments, the transmission mechanism 4700 can include one ormore linear actuators that produce translation (linear motion) of aportion of the tension members. Such transmission mechanisms caninclude, for example, a gimbal, a lever, or any other suitable mechanismto directly pull (or release) an end portion of any of the tensionmembers. For example, in some embodiments, the transmission mechanism4700 can include any of the transmission assemblies or componentsdescribed in U.S. Patent Application Pub. No. US 2015/0047454 A1 (filedAug. 15, 2014), entitled “Lever Actuated Gimbal Plate,” or U.S. Pat. No.6,817,974 B2 (filed Jun. 28, 2001), entitled “Surgical Tool HavingPositively Positionable Tendon-Actuated Multi-Disk Wrist Joint,” each ofwhich is incorporated herein by reference in its entirety. In otherembodiments however, the transmission mechanism 4700 can include acapstan or other motor-driven roller that rotates or “winds” a portionof any of the tension members to produce the desired tension membermovement. For example, in some embodiments, the transmission mechanism4700 can include any of the backend assemblies or components describedin U.S. Pat. No. 9,204,923 B2 (filed Jul. 16, 2008), entitled “MedicalInstrument Electronically Energized Using Drive Cables,” which isincorporated herein by reference in its entirety.

The instrument shaft 4410 can be any suitable elongated shaft thatcouples the wrist assembly 4500 to the transmission mechanism 4700.Specifically, the instrument shaft 4410 includes a proximal end portion4411 that is coupled to a housing of the transmission mechanism 4700,and a distal end portion 4412 that is coupled to the wrist assembly4500. The instrument shaft 4410 defines a passageway or series ofpassageways through which the tension members and other components(e.g., electrical wires, ground wires, or the like) can be routed fromthe transmission mechanism 4700 to the wrist assembly 4500. Althoughshown as being cylindrical, in other embodiments the instrument shaft4410 can have any suitable shape.

Referring to FIG. 10-13, the wrist assembly 4500 includes a proximalfirst link 4510 and a distal second link 4610. The first link 4510 has aproximal end portion 4511 and a distal end portion 4512. The proximalend portion 4511 is coupled to the distal end portion 4412 of theinstrument shaft 4410. The proximal end portion 4511 can be coupled tothe instrument shaft 4410 via any suitable mechanism. For example, insome embodiments, the proximal end portion 4511 can be matingly disposedwithin a portion of the instrument shaft (e.g., via an interferencefit). As shown, the proximal end portion 4511 can include one or moreprotrusions, recesses, openings, or connectors that couple the proximalend portion 4511 to the instrument shaft. The proximal end portion 4511can be fixedly coupled to the instrument shaft 4410 via an adhesivebond, a weld, or any other permanent coupling mechanism (i.e., acoupling mechanism that is not intended to be removed during normaluse).

The distal end portion 4512 includes a joint portion 4540 that isrotatably coupled to a mating joint portion 4640 of the second link4610. In this manner, the first link 4510 and the second link 4610 formthe wrist assembly 4500 having a first axis of rotation A₁ (alsoreferred to as the pitch axis) about which the second link 4610 canrotate relative to the first link 4510. A pin 4541 extends through thejoint portion 4540 of the distal end portion 4512 and the joint portion4640 of the second link 4610 to rotatably couple the second link 4610 tothe first link 4510. As shown in FIG. 10, the first link 4510 and thesecond link 4610 define a longitudinal centerline CL that intersects thepitch axis A₁ when the instrument is in an initial (or “straight”configuration).

Referring to FIG. 11, a first guide path 4515, a second guide path 4520,a third guide path 4525, and a fourth guide path 4535 are defined in thefirst link 4510. A first proximal end portion 4421 of the first tensionmember 4420 is movably disposed within the first guide path 4515. Afirst proximal end portion 4431 of the second tension member 4440 ismovably disposed within the second guide path 4520. A second proximalend portion 4441 of the first tension member 4420 is movably disposedwithin the third guide channel 4525. A second proximal end portion 4451of the second tension member 4440 is movably disposed within the fourthguide channel 4535. In this manner, the portions of the first tensionmember 4420 coupled to the first tool member 4462 are within guidechannels that are separated. In some embodiments, however, the firstguide path 4515 can be combined with the third guide channel 4525 toform a single channel within which the first proximal end portion 4421and the second proximal end portion 4441 of the first tension member4420 are disposed. In this manner, the portions of the second tensionmember 4440 coupled to the second tool member 4482 are within guidechannels that are separated. In some embodiments, however, the secondguide path 4520 can be combined with the fourth guide channel 4535 toform a single channel within which the first proximal end portion 4431and the second proximal end portion 4451 of the second tension member4440 are disposed.

The first link 4510 also defines additional bores or guide channels4550. The additional guide channels 4550 can contain (or allow passageof) various components of the wrist assembly, such as, for example,electrical wires. In some embodiments, the guide channels 4550 cancontain additional tension members (not shown) that are coupled to thesecond link 4610 and that cause the second link 4610 to rotate relativeto the first link 4510 (i.e., a pitch rotation) when the tension membersare moved. In this manner, the wrist assembly 4500 can be a six-tensionmember configuration (two tension members or portions of tension memberscontrolling the pitch rotation and four tension members or portions oftension members controlling the yaw and grip rotations).

The distal second link 4610 has a proximal end portion 4611 and a distalend portion 4612. As described above, the proximal end portion 4611includes a joint portion 4640 that is rotatably coupled to the jointportion 4540 of the first link 4510. The distal end portion 4612 of thesecond link 4610 includes a connector 4680 that is coupled to the endeffector 4460. In this manner, the first tool member 4462 and the secondtool member 4482 can rotate relative to the second link 4610 about asecond axis of rotation (also referred to as the yaw axis) A₂. Theconnector 4680 is a pin-type connector and includes the pin 4683 whichis supported by (and placed within) the pin openings 4682. In someembodiments, the connector 4680 can include any of the structure andfeatures of the pinned joints shown and described in U.S. Pat. No.9,204,923 B2 (filed Jul. 16, 2008), entitled “Medical InstrumentElectronically Energized Using Drive Cables,” which is incorporatedherein by reference in its entirety. As shown in FIG. 10, the secondaxis of rotation A₂ (also referred to as the yaw axis) is non-parallelto the pitch axis A₁. Thus, the instrument 4400 provides for up to threedegrees of freedom (i.e., a pitch motion about the first axis ofrotation A₁, a yaw rotation about the second axis of rotation A₂, and agrip motion about the second axis of rotation A₂).

Referring to FIGS. 11, 14A, 14B, 15A-C, the second link 4610 defines afirst thimble structure 4660, and a second thimble structure 4665. Thefirst thimble structure 4660 and the second thimble structure 4665 areeach formed as raised structures disposed on opposite side portions ofthe second link 4610 that each extend laterally outward from alongitudinal centerline CL of the second link 4610 (see FIG. 15A). Eachof the first and second thimble structures 4660, 4665 includes a smooth,contoured outer side surface 4661, 4662 that substantially extendsaround a perimeter of the corresponding first and second thimblestructure 4660, 4665 (see FIG. 14A). The first and second thimblestructures 4660, 4665 are disposed on opposite side portions of thesecond link 4610 such that the contoured outer side surfaces 4661, 4662each extend around an opposite end of the joint portion 4640 thatconnects with the joint portion 4540 of the first link, and each of theouter side surfaces extends around the first axis of rotation A₁.

The contoured outer side surfaces 4661, 4662 of the first and secondthimble structures 4660, 4665 are configured to act as support surfacesfor the tension members 4420, 4440 that can protect the tension membersfrom bending or kinking at high load-bearing regions within the secondlink 4610. As discussed below, the contoured outer side surfaces 4661,4662 are also configured to help guide the tension members 4420, 4440through curved guide paths 4615, 4620 that are defined in one side ofthe second link 4610 of the wrist assembly 4500 (see FIG. 14B), as wellas through similar curved guide paths (not shown) on the opposite sideof the second link. Referring to FIGS. 15B and 15C, each of thecontoured outer side surfaces 4661, 4662 are shaped to include a groovethat can enhance retention of portions of the tension members 4420, 4440that are in contact with the contoured outer side surfaces. The radiusof curvature for any point of contact along the contoured outer sidesurfaces 4661, 4662 with a portion of one of the tension member 4420,4440 can be determined as an effective radius of curvature, R_(bend). Asshown in FIGS. 15A and 15B, the effective radius of curvature, R_(bend),at any point along the contoured outer side surfaces 4661, 4662 is thesum of the instant radius of curvature within the groove at the pointalong the contoured outer side surfaces plus half the thickness (i.e.,the radius) of the tension member.

Referring to FIGS. 16A and 16B, this arrangement of the first and secondthimble structures 4660, 4665 allows a first distal central portion 4423of the first tension member 4420 and a first distal central portion 4433of the second tension member 4440 to each contact a portion of the outerside surface 4661 of the first thimble structure, depending on theorientation of the wrist assembly 4500. Although not shown, a secondcentral portion 4443 of the first tension member 4420 and a secondcentral portion 4443 of the second tension member 4440 can similarlycontact the outer side surface 4662 of the second thimble structure 4665located on the opposite side of the second link 4610. Thus, thisarrangement provides one thimble structure that functions to engage anddefine a portion of a guide path for two distinct tension memberportions. As shown in FIGS. 15B and 15B, the effective radius of aproximal end of the contoured outer side surfaces 4661, 4662 of thefirst and second thimble structures 4660, 4665 is identified asR_(bend), and is selected to produce the desired guide path, asdescribed further below.

Referring to FIG. 14B, the second link 4610 defines a first curved guidepath 4615 and a second curved guide path 4620. The second link 4610 alsoincludes a first guide surface 4616 and a second guide surface 4621 thatare portions of the contoured outer side surface 4661 of the firstthimble structure 4660. The second link 4610 also includes a third guidesurface 4617 that is aligned with a portion of the first curved guidepath 4615, and a fourth guide surface 4622 that is aligned with aportion of the second curved guide path 4620. The first and secondcurved guide paths 4615, 4620 (and therefore the portions of the firsttension member 4420 and the second tension member 4440 therein) are eachoffset from the longitudinal centerline CL and the first axis ofrotation A₁. In this manner, application of a force via the firsttension member 4420 or the second tension member 4440 produces a torqueabout the first axis of rotation A₁. This can result in rotation of thesecond link 4610 relative to the first link 4510 (i.e., pitch), as shownby the arrow OO in FIG. 17A for application of a force via the firsttension member 4420 or as shown by arrow NN in FIG. 17B for applicationof a force via the second tension member 4440. The amount of tensionmember offset from the longitudinal centerline CL is also based in parton the size of the thimble structure 4660. As shown in FIGS. 16A and16B, the outer surface 4661 of the thimble structure 4660 contacts thefirst central portion 4423 of the first tension member 4420 and thethird central portion 4433 of the second tension member 4440 when theinstrument 4400 is in certain orientations. Thus, the effective radiusR_(bend) of the thimble structure 4660 defines the amount of offset.

As shown in FIG. 13, the end effector 4460 includes a first tool member4462 and a second tool member 4482. The first tool member 4462 includesa contact portion 4464 and a pulley portion 4467. The contact portion4464 is configured engage or manipulate a target tissue during asurgical procedure. Although shown as being a gripping surface, in otherembodiments the contact portion 4464 can be any suitable surface of thetypes shown and described herein (e.g., a cutter, a tissue manipulator,a cauterizing surface, or the like). As shown in FIGS. 10 and 11, thepulley portion 4467 is rotatably coupled to the second link 4610 via thepin 4683. In this manner, the first tool member 4462 can rotate aboutthe pin 4683 and relative to the second link 4610 via the second axis ofrotation A₂. Moreover, the pulley portion 4467 defines the couplingopenings 4472 within which the first distal end portion 4422 of thefirst tension member 4420 is coupled. The outer surface of the pulleyportion 4467 is offset from the yaw axis A₂. In this manner, applicationof a force by the first tension member 4420 on the pulley portion 4467produces a torque on the first tool member 4462 about the yaw axis A₂,which can result in rotation of the first tool member 4462 or theapplication of a gripping force.

As shown in FIG. 13, the second tool member 4482 includes a contactportion 4484 and a pulley portion 4487. The contact portion 4484 isconfigured engage or manipulate a target tissue during a surgicalprocedure. Although shown as being a gripping surface, in otherembodiments the contact portion 4484 can be any suitable surface of thetypes shown and described herein (e.g., a cutter, a tissue manipulator,a cauterizing surface, or the like). As shown in FIGS. 10 and 11, thepulley portion 4487 is rotatably coupled to the second link 4610 via thepin 4683. In this manner, the second tool member 4482 can rotate aboutthe pin 4683 and relative to the second link 4610 via the second axis ofrotation A₂. As shown in FIG. 11, the pulley portion 4487 defines thecoupling openings 4472 within which the distal end portion 4432 of thesecond tension member 4440 is coupled. The outer surface of the pulleyportion 4487 is offset from the yaw axis A₂. In this manner, applicationof a force by the second tension member 4440 on the pulley portion 4487produces a torque on the second tool member 4482 about the yaw axis A₂,which can result in rotation of the second tool member 4482 or theapplication of a gripping force.

As shown in FIG. 12, the first tension member 4420 has a first proximalend portion 4421, a first proximal central portion 4425, a first distalcentral portion 4423, and a first distal end portion 4422 on one side ofa first tension member loop, as well as a second central portion 4443and a second proximal end portion 4441 along with the first distal endportion 4422 on the other side of the first tension member loop. Thesecond tension member 4440 has a third proximal end portion 4431, athird proximal central portion 4427, a third distal central portion4433, and a third distal end portion 4432 on one side of a secondtension member loop, as well as a fourth central portion 4453 and afourth proximal end portion 4451 along with the fourth distal endportion on the other side of the second tension member loop. Theproximal end portions 4421, 4441, 4431, 4451 each extend outside of thewrist assembly 4500, through the instrument shaft 4410, and into thetransmission mechanism 4700. As described above, the transmissionmechanism 4700 can move the proximal end portions 4421, 4441, 4431, 4451to produce a resulting movement (or force) at the respective distal endportions 4422, 4432 of the tension members. The first and second tensionmembers 4420 and 4440 can have any suitable shape. The use of thetension members can provide for a low-cost, disposable instrument thatis suitable for minimally-invasive surgical procedures. In use, thedistal end portion of the instrument 4400 provides for up to threedegrees of freedom, and can be moved between multiple differentconfigurations to perform a variety of surgical operations.

Referring to FIG. 16A, the first proximal central portion 4425 of thefirst tension member 4420 and the third proximal central portion 4427 ofthe second tension member 4440 are retained within the first and secondcurved guide paths 4615, 4620 on one side of the second link 4610, asdescribed above along with FIG. 14B. The shape of the first and secondcurved guide paths 4615, 4620 are such that the first tension member4420 and the second tension member 4440 are routed through the wristassembly 4500 in a manner that maintains the desired bend geometry,tension member tension, and the like therein during actuation of theinstrument 4400. This includes routing the first and second tensionmembers 4420, 4440 in a low-friction, parallel-alignment manner withrespect to the first and second curved guide paths 4615, 4620 asdescribed below along with FIGS. 16B, 17A and 17B. Similarly, the secondcentral portion 4443 of the first tension member 4420 and the fourthcentral portion 4453 of the second tension member 4440 are retainedwithin corresponding third and fourth curved guide paths (not shown), asdescribed above for the first and second curved guide paths 4615, 4620.The shape of the third and fourth curved guide paths (not shown) aresuch that the first tension member 4420 and the second tension member4440 are routed through the wrist assembly 4500 in a manner thatmaintains the desired bend geometry, tension member tension, and thelike during actuation of the instrument 4400. This likewise includesrouting the first and second tension members 4420, 4440 in alow-friction manner as described below along with FIGS. 16B, 17A and 17Bfor the first and second curved guide paths 4615, 4620. As describedabove, the first distal end portion 4422 is coupled to the first toolmember 4462 and the third distal end portion 4432 is coupled to thesecond tool member 4482 via a pin or swage coupling (i.e., within thecoupling openings 4472, 4472). In this manner, as described herein,movement of (or a force applied to) the tension members can producepitch, yaw, grip or any combination of these motions.

Referring to FIGS. 16A and 16B, the third guide surface 4617 is formedalong a distal portion of the first curved guide path 4615 and is curvedinward with respect to the first curved guide path 4615 such that firstguide surface 4616 and the third guide surface 4617 are convex withrespect to each other and with respect to the first curved guide path4615. Further, the third guide surface 4617 has an effective radius ofcurvature R₁ that includes the radius of curvature of the third guidesurface 4617 plus the thickness (i.e., radius for a circular tensionmember) of the first tension member 4420. The third guide surface 4617is configured to guide the first distal central portion 4423 of thefirst tension member 4420 through the first curved guide path 4615 suchthat the portion of the first tension member 4420 disposed between thefirst distal end portion 4422 and first distal central portion 4423 arein parallel alignment with the pulley portion 4467 of the end effector4460 while in the first orientation shown in FIG. 16A, as well as whenin the second orientation shown in FIG. 17A, the third orientation shownin FIG. 17B, and orientations therebetween. As such, the third guidesurface can reduce frictional contact between the first tension member4420 and the end effector 4460 including the pulley portion 4467 duringmovements of the wrist assembly 4500 by maintaining parallel alignmentof the first tension member between the second link 4610 and the endeffector 4460. In addition, as discussed further below along with FIG.17A, the third guide surface is configured to guide the first distalcentral portion 4423 of the first tension member 4420 while in thesecond orientation shown in FIG. 17A, such that the first proximalcentral portion 4425 is retained in parallel alignment with the firstguide path 4515 of the first link 4510. The fourth guide surface 4622 islikewise configured to guide portions of the second tension member 4440in a similar manner with respect to the second guide path 4620.

Referring to FIGS. 16A, 16B, and 17B, at least the first guide surface4616 of the second link 4610 contacts the first distal central portion4423 of the first tension member 4420 when the second link 4610 is inthe first orientation shown in FIGS. 10, 16A and 16B and when the secondlink 4610 is in other orientations, such as the third orientation shownin FIG. 17B. Similarly stated, the first distal central portion 4423 ofthe tension member 4420 is in contact with the first guide surface 4616throughout a portion of the angular range of motion of the second link4610 relative to the first link 4510. The first guide surface 4616guides the path of the first tension member 4420 to transition withinthe second curved guide path 4620 while in the first orientation shownin FIG. 16A and also when the second link 4610 rotates relative to thefirst link 4510 in direction NN shown in FIG. 17B. Further, the firstguide surface 4616 is configured to do so while also maintaining thefirst proximal central portion 4425 and the first proximal end portion4421 of the first tension member 4420 in parallel alignment with thecenterline CL₂ of the first guide path 4515 of the first link 4510.

In particular, the first guide surface 4616 is sized and positioned suchthat the first proximal end portion 4421, the first proximal centralportion 4425, or both the first proximal end portion 4421 and the firstproximal central portion 4425 of the first tension member 4420 areretained in parallel alignment with the centerline CL₂ of the firstguide path 4515 of the first link 4510 throughout a portion of theangular range of motion of the second link 4610 relative to the firstlink 4510. As such, the first tension member 4420 can move within thefirst curved guide path 4615 in the directions shown by arrow A-B ofFIG. 16A without contacting surfaces within the first guide path 4515 ofthe first link. In this manner, frictional contact is reduced formovements of the first tension member 4420 for at least the angularrange of motion in direction NN. In some embodiments, the first guidesurface 4616 has an effective radius of curvature R_(bend) about thefirst axis of rotation A₁ that is equal to the distance d₁ shown in FIG.16A, such that the first proximal end portion 4421, the first proximalcentral portion 4425, or both the first proximal end portion 4421 andthe first proximal central portion 4425 of the first tension memberremain parallel to the centerline CL₂ over a portion of the range ofmotion of the second link 4610. Although shown as being a single radiusof curvature R_(bend), in other embodiments the first guide surface 4616can be a curved surface that is characterized by multiple differentradii of curvature.

Referring to FIGS. 16A and 17A, at least the second guide surface 4621of the second link 4610 contacts the third distal central portion 4433of the second tension member 4440 when the second link 4610 is in thefirst orientation shown in FIGS. 10 and 16A, as well as when the secondlink 4610 is in other orientations, such as in the second orientationshown in FIG. 17A. Similarly stated, the third distal central portion4433 of the second tension member 4440 is in contact with (e.g., wrapsaround as shown in FIG. 17A) the second guide surface 4621 throughout aportion of the angular range of motion of the second link 4610 relativeto the first link 4510. The second guide surface 4621 guides the path ofthe second tension member 4440 to transition within the second curvedguide path 4620 while in the first orientation shown in FIG. 16A, aswell as when the second link 4610 rotates relative to the first link4510 in direction OO shown in FIG. 17A. Further, the second guidesurface 4621 is configured to do so while also maintaining the secondproximal central portion 4426 and the second proximal end portion 4431of the second tension member 4440 in parallel alignment with thecenterline CL₃ of the second guide path 4520 of the first link 4510.

In particular, the second guide surface 4621 is sized and positionedsuch that the second proximal end portion 4431, the second proximalcentral portion 4426, or both the second proximal end portion 4431 andthe second proximal central portion 4426 of the second tension member4440 are retained in parallel alignment with the centerline CL₃ of thesecond guide path 4520 throughout a portion of the angular range ofmotion. As such, the second tension member 4440 can move within thesecond guide path 4520 of the first link in the directions shown byarrow AB of FIG. 16A without contacting surfaces within the second guidepath. In this manner, frictional contact is reduced for movements of thesecond tension member 4440 for at least the angular range of motion indirection OO. In some embodiments, the second guide surface 4621 has aneffective radius of curvature R_(bend) about the first axis of rotationA₁ that is equal to the distance d₁ shown in FIG. 16A, such that thesecond proximal end portion 4431, the second proximal central portion4426, or both the second proximal end portion 4431 and the secondproximal central portion 4426 of the second tension member remainparallel to the centerline CL₃ over a portion of the range of motion ofthe second link 4610. Although shown as being a single radius ofcurvature R_(bend), in other embodiments the second guide surface 4621can be a curved surface that is characterized by multiple differentradii of curvature.

In use, the wrist assembly 4500 can be moved between variousorientations. As shown by the arrow OO in FIG. 17A, the wrist assembly4500 can be moved between a first (or straight) orientation and a secondorientation by rotating the second link 4610 relative to the first link4510 about the first axis of rotation A₁. Similarly, the second link4610 can be rotated in an opposite direction as shown by the arrow NN inFIG. 17B about the first axis of rotation A₁ to a third orientationshown in FIG. 17B. When the wrist assembly 4500 is in the firstorientation shown in FIG. 16A, the first tension member 4420 is withinthe first curved guide path 4615 and the second tension member 4440 iswithin the second curved guide path 4620. More particularly, the firstdistal central portion 4423 is in contact with the first guide surface4616 of the second link 4610 and the outer side surface 4661 of thethimble structure 4660. The third distal central portion 4433 is incontact with the second guide surface 4621 of the second link 4610 andthe outer side surface 4661 of the thimble structure 4660. When thefirst tension member 4420 and the second tension member 4440 are movedin the same direction (e.g., to produce a yaw motion of the end effector4460), the first distal central portion 4423 and the third distalcentral portion 4433 will slide against the outer side surface 4661,which maintains the first proximal central portion 4425 and the secondproximal central portion 4426 of the first and second tension members4420, 4440 in parallel alignment with the centerlines CL₂, CL₃ of thefirst and second guide paths 4515, 4520 of the first link 4510.

When the wrist assembly 4500 is in the second orientation (FIG. 17A),the first distal central portion 4423 of the first tension member 4420remains within the first curved guide path 4615, but is spaced apartfrom the first guide surface 4616 and wrapped around and in contact withthe third guide surface 4617. Moreover, the first distal central portion4423 is spaced apart from the thimble structure 4660 and the outer sidesurface 4661 thereof along with the first guide surface 4616, such thatthe first distal central portion 4423 is guided within the first curvedguide path 4615 primarily by the third curved guide surface 4617.

The third guide surface 4617 has an effective radius of curvature R₁that includes the radius of curvature of the third guide surface 4617plus half the thickness (i.e., radius for a circular tension member) ofthe first tension member 4420. The effective radius of curvature R₁ isconfigured to guide the first proximal central portion 4425 of the firsttension member 4420 to be in parallel alignment with the centerline CL₂of the first guide path 4515 of the first link 4510 while the wristassembly 4500 is in the second orientation shown in FIG. 17A. Thus, thefirst proximal central portion 4425 and the first proximal end portion4421 of the first tension member 4420 can be maintained in parallelalignment within the first guide path 4515 of the first link 4510throughout the angular range of motion of the second link 4610 betweenthe second orientation shown in FIG. 17A, through the first orientationshown in FIGS. 16A and 16B as discussed above, and to the thirdorientation shown in FIG. 17B as discussed below. Thus, frictionalcontact between the first tension member 4420 within the first guidepath 4515 of the first link can be avoided through an angular range ofmotion of the wrist assembly 4500, which reduces the overall frictionfor movements thereof.

When the wrist assembly 4500 is in the third orientation (FIG. 17B), thethird distal central portion 4433 of the second tension member 4440remains within the second curved guide path 4620, but is spaced apartfrom the second guide surface 4621. As such, the third distal centralportion 4433 is wrapped around and in contact with the fourth guidesurface 4622, which thereby guides the distal central portion tomaintain the second proximal central portion 4426 in parallel alignmentwith the centerline CL₃ of the second guide path 4520 of the first link4510. Moreover, the third distal central portion 4433 is spaced apartfrom the thimble structure 4660, such that the second distal centralportion is guided within the second curved guide path 4620 primarily bythe fourth guide surface 4622.

The fourth guide surface 4622 has an effective radius of curvature R₁that includes the radius of curvature of the fourth guide surface 4622plus half the thickness (i.e., radius for a circular tension member) ofthe second tension member 4440. The effective radius of curvature R₁ isconfigured to guide the second proximal central portion 4426 of thesecond tension member 4440 to be in parallel alignment with thecenterline CL₃ of the second guide path 4520 of the second link 4610while the wrist assembly 4500 is in the third orientation shown in FIG.17B. Thus, the second proximal central portion 4426 and the secondproximal end 4431 of the second tension member 4440 can be maintained inparallel alignment within the second guide path 4520 of the first link4510 throughout the angular range of motion of the second link 4610between the second orientation shown in FIG. 17A, through the firstorientation shown in FIGS. 16A and 16B as discussed above, and to thethird orientation shown in FIG. 17B. Thus, frictional contact betweenthe second tension member 4440 within the second guide path 4520 of thefirst link can be avoided through an angular range of motion of thewrist assembly 4500, which reduces the overall friction for movementsthereof.

Referring again to FIGS. 16A and 16B, the first tension member 4420 andthe second tension member 4440 are configured for low-friction axialmovements when the first and second proximal end portions 4421 and 4431are moved in accordance with the actuator (not shown) as describedabove, which moves the first proximal end portion in the direction ofarrows A-B shown in FIG. 16A. As such, the effective radius, Rh end, ofthe outer side surface 4661 of the thimble structure 4660 at theproximal end of the thimble structure, which includes the first andsecond guide surfaces 4616, 4621, is configured to be the same as thedistance, d₁, that the centerlines, CL₂ and CL₃, of the first and secondguide paths 4515, 4520 of the first link 4510 are offset from thecenterline CL₁ of the shaft. Stated differently, the effective radius ofthe first and second guide surfaces, 4616, 4621 (i.e., R_(bend)) areconfigured to be equal to the offset distance (i.e., d₁) of the firstlink guide surfaces 4616, 4621, such that R_(bend)=d₁. This relationshipmaintains the first and second proximal central portions 4425, 4426 andthe first and second proximal end portions 4421, 4431 of the first andsecond tension members 4420, 4440 in parallel alignment within andthrough the first and second guide paths 4515, 4520 of the first link4510 while the wrist assembly is in the first orientation shown in FIGS.16A and 16B.

The relationship of R_(bend)=d₁ further maintains this parallelalignment through a portion of the angular rotation for the second link4610 with respect to the first link 4510 about the first axis ofrotation A₁ while the first distal central portion 4423 is in contactwith the first guide surface 4616 (FIG. 17B), and while the third distalcenter portion 4433 is in contact with the second guide surface 4621(FIG. 17A). This is because the first and/or second guide surface 4616.4621 are formed as portions of the outer side surfaces 4661 of thethimble structure 4660, which have as their effective radius ofcurvature, R_(bend), that is equal to d₁ with respect to the first axisof rotation A₁ located along the shaft centerline CL₁. As such, thefirst and/or second proximal central portions 4425, 4426 are retained inparallel alignment with the first and second guide path centerlines CL₂and CL₃ in the first link 4510 that are also offset from the shaftcenterline by the same distance d₁ while in the second orientation (FIG.17A) and in the third orientation (FIG. 17B). For example, FIG. 17Ashows the second tension member 4440 wrapping around a portion of thethimble structure 4660 for the second orientation such that the thirddistal portion 4433 is in contact with the second guide surface 4621having an effective radius R_(bend) that is equal to d₁ with respect toaxis A₁ and shaft centerline CL₁, which thereby retains the secondproximal central portion 4426 in parallel alignment with the secondguide path 4520 through the first link 4510. Likewise, FIG. 17B showsthe second tension member 4420 wrapping around a portion of the thimblestructure 4660 for the third orientation such that the first distalcentral portion 4423 is in contact with the first surface 4616 having aneffective radius R_(bend) that is equal to d₁ with respect to axis A₁and shaft centerline CL₁, which thereby retains the first proximalcentral portion 4425 in parallel alignment with the first guide path4515 through the first link 4510.

With further reference to FIGS. 16A and 16B, the first tension member4420 and the second tension member 4440 are additionally configured toprovide low-friction axial movements while in the first orientationbased on: (i) the effective radius of curvature R₁, of the third andfourth guide surfaces 4617, 4622; (ii) the effective radius of curvatureR_(bend) for the first and second guide surfaces 4616, 4621; and (iii)the perpendicular offset distance of the axis, A_(R1), for R₁ from theshaft centerline, CL₁. As shown in FIG. 16A, the effective radii ofcurvature R₁, of the third and fourth guide surfaces 4617, 4622 eachhave an axis, A_(R1), for the radius of curvature that isperpendicularly offset from the shaft centerline, CL₁, of the wrist byan offset distance d₂ on opposite sides of the shaft centerline. Arelationship is provided between the perpendicular offset distance d₂,the effective radii of curvatures R₁, and the radius of curvatureR_(bend), for the first orientation shown in FIG. 16A, such that theperpendicular offset distance d₂, is less than the sum of the effectiveradius of curvature R₁ plus the radius of curvature R_(bend), (i.e.,d₂<R_(bend)+R₁). Such a relationship for the first orientation ensuresthat the first and third distal central portions 4423, 4433 of the firstand second tension members 4420, 4440 are each guided inward toward thecenterline CL of the wrist assembly 4500 through guide first and secondcurved guide paths 4615, 4620, which is concurrent with the shaftcenterline CL₁ in the first orientation shown in FIG. 16A. The first andthird distal central portions 4423, 4433 are guided inward within thecorresponding first or second curved guide paths 4615, 4620 from a pointof contact with the first or second guide surface 4616, 4621 to a pointof contact with the corresponding third or fourth guide surface 4617,4622. As such, each of the first and third distal central portions 4423,4433 is biased into contact with the corresponding first or second guidesurface 4616, 4621 and with the corresponding third or fourth guidesurface 4617, 4622 for the respective first or second curved guide paths4615, 4620 while in the first orientation, which aligns the first andsecond proximal central portions 4425, 4426 in parallel alignment withthe corresponding first and second first guide paths 4515, 4420 of thefirst link 4510.

As shown in FIG. 16A, the second link 4610 is configured to rotate withrespect to the first link 4510 about the first axis of rotation, A₁. Thesecond link 4610 rotates in the indicated direction OO for angularrotation Θ to rotate from the first orientation to the secondorientation shown in FIG. 17A. In some embodiments, the angularrotation, Θ, from the first to the second orientation can be a maximumangular rotation Θ for the second link 4610 with respect to the firstlink 4510. As the second link 4610 rotates from the first orientation tothe second orientation, the third and fourth guide surfaces 4617, 4622,the corresponding effective radii of curvature, R₁, and the curvatureaxis, A_(R1), also rotate by angular rotation Θ about the first axis,A₁. The rotation changes the location of the curvature axis, A_(R1), forthe third guide surface 4617 and its perpendicular offset distance, d₂,from the shaft centerline CL in the first orientation to a rotatedposition for the second orientation as shown in FIG. 17A, which isoffset by a perpendicular distance d₂′ from the shaft centerline CL.

In embodiments in which the second link 4610 is rotated at a maximumangular rotation, Θ, for the second orientation, the perpendicularoffset distance d₂′ from the shaft centerline CL to the axis, A_(R1),for the third guide surface 4617 is equal to the shaft offset distanced₁ of the centerline CL₂ of the first guide path 4515 in the first link4510 plus the corresponding radius of curvature, R₁, of the third guidesurface 4617. Stated differently, d₂′ (curvature axis perpendicularoffset at maximum rotation) is equal to the sum of d₁ (first guide pathperpendicular offset) and R₁ (radius of distal third guide surface)(i.e., d₂′=d₁+R₁), which maintains parallel alignment of the firstproximal central portion 4425 with the first guide path 4515 at maximumangular rotation in direction OO. Whereas, for the first orientation ofFIG. 16A, d₂ (curvature axis perpendicular offset in first orientation),is less than the sum of d₁ and R₁ (i.e., d₂<d₁+R₁), which maintainsparallel alignment of the first proximal central portion 4425 with thefirst guide path 4515 at that orientation. This is due to the firstdistal central portion 4423 of the first tension member 4420 beingretained against the third guide surface 4617 in the second orientationat the maximum angular rotation, Θ, such that the first proximal centralportion 4425 and the first proximal end portion 4421 are in parallelalignment with the first guide path 4515. Thus, the first tension member4420 can move freely in the longitudinal direction within the firstguide path 4515 in the second orientation at its maximum angularrotation without frictional contact with surfaces within the first guidepath.

Referring to FIGS. 14B and 16B, the thimble structure 4660 includes aproximal region 4663 and a distal region 4664. The outer side surface4661 of the proximal region 4663 includes the first guide surface 4616on one side of the centerline CL of the shaft and the second guidesurface 4621 on the opposite second side of the centerline. In addition,the proximal region 4663 is curved according to the radius of curvatureR_(bend) about the axis of rotation A₁. In contrast, the outer sidesurface 4661 within the distal region 4664 is not curved according theradius of curvature R_(bend). Rather, the outer side surface 4661 withinthe distal region 4664 is configured to have a contour that generallyfollows the contour of the portions of the first and second tensionmembers 4420, 4440 proximate to the outer side wall therein while in thefirst orientation shown in FIG. 16B. Such contour portions of the outerside surface 4661 can provide additional guide surfaces along the firstand second curved guide paths 4615 and 4620 for guiding the first andsecond tension members 4420, 4440 during movements within the guidepaths.

In some embodiments, the thimble structure can be configured to includethe proximal region 4663 of the thimble structure 4660 without includingthe distal region 4664. As such, the thimble structure 4660 shown inFIGS. 14B and 16B can be configured to include the portions of the outerside surface 4661 that form the first guide surface 4616 and the secondguide surface 4621, which are curved to have the radius of curvatureR_(bend), without including remaining portions of the outer side surface4661 that are not curved according to the radius of curvature R_(bend)(and corresponding portions of the thimble structure 4660). In otherwords, the thimble structure can be configured to have a roundpulley-like shape, which can be fixed with respect to the second link4610 or mounted as a pulley for rotation with respect to the second link4610. Such embodiments can further avoid potential frictional contactbetween the first and second tension members 4420, 4440 and surfacesdisposed along the first and second curved guide paths 4615, 4620 fromdistal portions of the thimble during longitudinal movements of thetension members therein. For example, FIGS. 18-25 show various views ofan instrument 5400, according to an embodiment, in which the thimblestructure is configured as a pulley that lacks a distal portion andcorresponding surfaces, and that rotates relative to the second link5610. The instrument 5400 generally includes the aspects and features ofinstrument 4400 discussed above along with FIGS. 10-17B, except asdiscussed below along with FIGS. 18-25.

Similar to instrument 4400, the instrument 5400 includes a transmissionmechanism (that can function as an actuator mechanism), an instrumentshaft 5410, a wrist assembly 5500, and an end effector 5460. Referringto FIG. 18, the instrument 5400 also includes a first tension member5420 and a second tension member 5440 that couple the transmissionmechanism to the wrist assembly 5500. The instrument 5400 is configuredsuch that movement of the cables can produce rotation of the wristassembly 5500 (i.e., pitch rotation) about a first axis of rotation A₁,yaw rotation of the end effector 5460 about a second axis of rotationA₂, grip rotation of the tool members of the end effector 5460 about theyaw axis, or any combination of these movements. Changing the pitch,yaw, or grip of the instrument 5400 can be performed by manipulating thefour cables in similar manner as that described above for theinstruments 3400 and 4400. Thus, the specific movement of each of thefour cables to accomplish the desired motion is not described below.Although shown and described as including two cables that are wrappedabout the end effector 5460 resulting in four proximal end cableportions (i.e., the four-cable arrangement), in other embodiments theinstrument 5400 can include additional cables that separately change thepitch of the instrument 5400.

Referring to FIGS. 18 and 19, the wrist assembly 5500 includes a firstlink 5510 and a second link 5610. The first link 5510 has a proximal endportion 5511 and a distal end portion 5512. The proximal end portion5511 is coupled to the distal end portion 5412 of the instrument shaft5410. The proximal end portion 5511 can be coupled to the instrumentshaft 5410 via any suitable mechanism. For example, in some embodiments,the proximal end portion 5511 can be matingly disposed within a portionof the instrument shaft (e.g., via an interference fit). As shown, theproximal end portion 5511 can include one or more protrusions, recesses,openings, or connectors that couple the proximal end portion 5511 to theinstrument shaft. The proximal end portion 5511 can be fixedly coupledto the instrument shaft 5410 via an adhesive bond, a weld, or any otherpermanent coupling mechanism (i.e., a coupling mechanism that is notintended to be removed during normal use).

The distal end portion 5512 includes a joint portion 5540 that isrotatably coupled to a mating joint portion 5640 of the second link5610. In this manner, the first link 5510 and the second link 5610 formthe wrist assembly 5500 having a first axis of rotation A₁ (alsoreferred to as the pitch axis) about which the second link 5610 canrotate relative to the first link 5510. A pin 5541 extends through jointportion 5540 of the distal end 5512 and the joint portion 5640 of thesecond link 5610 to rotatably couple the second link 5610 to the firstlink 5510. As shown in FIG. 18, the first link 5510 and the second link5610 define a longitudinal centerline CL that intersects the pitch axisA₁ when the instrument is in an initial (or “straight” configuration).

The second link 5610 has a proximal end portion 5611 and a distal endportion 5612. As described above, the proximal end portion 5611 includesa joint portion 5640 that is rotatably coupled to the joint portion 5540of the first link 5510. The distal end portion 5612 of the second link5610 includes a connector 5680 that is coupled to the end effector 5460.In this manner, the first tool member 5462 and the second tool member5482 can rotate relative to the second link 5610 about a second axis ofrotation (also referred to as the yaw axis) A₂. The connector 5680 is apin-type connector and includes the pin 5683 which is supported by (andplaced within) the pin openings. In some embodiments, the connector 5680can include any of the structure and features of the pinned joints shownand described in U.S. Pat. No. 9,204,923 B2 (filed Jul. 16, 2008),entitled “Medical Instrument Electronically Energized Using DriveCables,” which is incorporated herein by reference in its entirety. Asshown in FIG. 10, the second axis of rotation A₂ (also referred to asthe yaw axis) is non-parallel to the pitch axis A₁. Thus, the instrument5400 provides for up to three degrees of freedom (i.e., a pitch motionabout the first axis of rotation A₁, a yaw rotation about the secondaxis of rotation A₂, and a grip motion about the second axis of rotationA₂).

Referring to FIGS. 20, 23 and 25, the second link 5610 includes a firstpulley 5660 (which functions as a first thimble member), and a secondpulley 5665 (which functions as a second thimble member). The firstpulley 5660 and the second pulley 5665 are each rotatably coupled to thesecond link 5610 via the pin 5541. In this manner, the first pulley 5660and the second pulley 5665 can each rotate relative to the second link5610 about the first axis of rotation A₁. In other embodiments (notshown), the first pulley 5660 and the second pulley 5665 can be fixedlyattached to the second link 5610. The first pulley 5660 includes anouter surface 5661 within a grooved channel (see FIG. 25), and thesecond pulley 5665 includes an outer surface 5666 within a groovedchannel (see FIG. 25). This arrangement allows the first distal centralportion 5423 of the first tension member 5420 and second distal centralportion 5433 of the second tension member 5440 to each contact the outersurface 5661 of the first pulley (see FIGS. 23 and 24), depending on theorientation of the wrist assembly 5500. Although not shown, the thirdcentral portion of the first tension member 5420 and the fourth centralportion of the second tension member 5440 can similarly contact theouter surface 5666 of the second pulley 5665. Thus, this arrangementprovides one pulley that functions to engage and define a portion of aguide path for two distinct cable portions. As shown in FIG. 23, theradius of the first pulley 5660 and the second pulley 5665 is identifiedas R_(pulley), and is selected to produce the desired guide path, asdescribed below.

As shown in FIG. 23, the second link 5610 defines a first curved guidepath 5615 and a second curved guide path 5620. The second link 5610 alsoincludes a first guide surface 5616 and a third guide surface 5617 thatare aligned with a portion of the first curved guide path 5615. Thesecond link 5610 also includes a second guide surface 5621 and a fourthguide surface 5622 that are aligned with a portion of the second curvedguide path 5620. The first and second curved guide paths 5615, 5620 (andtherefore the portions of the first tension member 5420 and the secondtension member 5440 therein) are each offset from the longitudinalcenterline CL and the first axis of rotation A₁. In this manner,application of a force via the first tension member 5420 or the secondtension member 5440 produces a torque about the first axis of rotationA₁. This can result in rotation of the second link 5610 relative to thefirst link 5510 (i.e., pitch), as shown by the arrow OO in FIG. 22 forapplication of a force via the first tension member 5420. The amount oftension member offset from the longitudinal centerline CL is also basedin part on the size of the pulley 5660. As shown in FIG. 23, the outersurface 5661 of the pulley 5660 contacts the first distal centralportion 5423 of the first tension member 5420 and the second distalcentral portion 5433 of the second tension member 5440 when theinstrument 5400 is in certain orientations. Thus, the radius R_(pulley)of the pulley 5660 defines the amount of offset.

In use, the wrist assembly 5500 can be moved between variousorientations. As shown by the arrow OO in FIG. 22, the wrist assembly5500 can be moved between a first (or straight) orientation and a secondorientation by rotating the second link 5610 relative to the first link5510 about the first axis of rotation A₁. Similarly, the second link5610 can be rotated in an opposite direction about the first axis ofrotation A₁ to a third orientation (not shown). When the wrist assembly5500 is in the first orientation, the first tension member 5420 iswithin the first curved guide path 5615 (e.g., a first tension memberpath) and the second tension member 5440 is within the second curvedguide path 5620 (e.g., a second tension member path). More particularly,the first distal central portion 5423 is in contact with the first guidesurface 5616 of the second link 5610 and the outer surface 5661 of thepulley 5660. The second distal central portion 5433 is in contact withthe third guide surface 5617 of the second link 5610 and the outersurface 5661 of the pulley 5660.

As discussed above along with wrist assembly 4500 and as shown in FIGS.19, 20 and 23, the first and second tension members 5420, 5440 arerouted through the first and second curved guide paths 5615, 5620 in alow-friction, parallel-alignment manner with respect to the first andsecond guide paths 5515, 5520 in the first link 5510. Similarly, thesecond central portion of the first tension member 5420 and the fourthcentral portion of the second tension member 5440 are retained withincorresponding third and fourth curved guide paths (not shown), asdescribed herein for the first and second curved guide paths 5615, 5620.The shape of the third and fourth curved guide paths (not shown) aresuch that the first tension member 5420 and the second tension member5440 are routed through the wrist assembly 5500 in a manner thatmaintains the desired bend geometry, tension member tension, and thelike during actuation of the instrument 5400. This likewise includesrouting the first and second tension members 5420, 5440 in a similarparallel, low-friction manner.

Referring to FIGS. 20 and 23, the third guide surface 5617 is formedalong a distal portion of the first curved guide path 5615 and is curvedinward with respect to the first curved guide path 5615 such that firstguide surface 5616 and the third guide surface 5617 are convex withrespect to each other and with respect to the first curved guide path5615. Further, the third guide surface 5617 has an effective radius ofcurvature R₁ that includes the radius of curvature of the third guidesurface 5617 plus the thickness (i.e., radius for a circular tensionmember) of the first tension member 5420. The third guide surface 5617is configured to guide the first distal central portion 5423 of thefirst tension member 5420 through the first curved guide path 5615 suchthat the portion of the first tension member 5420 disposed between thefirst distal end portion 5422 and first distal central portion 5423 arein parallel alignment with the pulley portion 5467 of the end effector5460 while in the first orientation shown in FIGS. 20 and 23, as well aswhen in the second orientation shown in FIGS. 21 and 24, in a thirdorientation rotated opposite from the second orientation (not shown),and in orientations therebetween. As such, the third guide surface 5617can reduce frictional contact between the first tension member 5420 andthe end effector 5460 including the pulley portion 5467 during movementsof the wrist assembly 5500 by maintaining parallel alignment of thefirst tension member between the second link 5610 and the end effector5460.

Referring to FIGS. 19, 20 and 23, at least the second guide surface 5621of the second link 5610 contacts the second distal central portion 5433of the second tension member 5440 when the second link 5610 is in thefirst orientation shown in FIGS. 19, 20 and 23, as well as when thesecond link 5610 is in other orientations, such as in the secondorientation shown in FIGS. 21 and 24. Similarly stated, the seconddistal central portion 5433 of the second tension member 5440 is incontact with (e.g., wraps around as shown in FIGS. 21, 22 and 24) thesecond guide surface 5621 throughout a portion of the angular range ofmotion of the second link 5610 relative to the first link 5510. Thesecond guide surface 5621 guides the path of the second tension member5440 to transition within the second curved guide path 5620 while in thefirst orientation shown in FIGS. 19, 20 and 23, as well as when thesecond link 5610 rotates relative to the first link 5510 in direction OOshown in FIG. 22. Further, the second guide surface 5621 is configuredto do so while also maintaining the second proximal central portion 5426and the second proximal end portion 5431 of the second tension member5440 in parallel alignment with the centerline CL₃ of the second guidepath 5520 of the first link 5510.

In particular, the second guide surface 5621 is sized and positionedsuch that the second proximal end portion 5431, the second proximalcentral portion 5426, or both the second proximal end portion 5431 andthe second proximal central portion 5426 of the second tension member5440 are retained in parallel alignment with the centerline CL₃ of thesecond guide path 5520 throughout a portion of the angular range ofmotion. As such, the second tension member 5440 can move within thesecond guide path 5520 of the first link in the directions shown byarrow A-B of FIG. 19 without contacting surfaces within the second guidepath. In this manner, frictional contact is reduced for movements of thesecond tension member 5440 for at least the angular range of motion indirection OO. In some embodiments, the second guide surface 5621 has aneffective radius of curvature R_(bend) about the first axis of rotationA₁ that is equal to the distance d₁ shown in FIG. 16A, such that thesecond proximal end portion 5431, the second proximal central portion5426, or both the second proximal end portion 5431 and the secondproximal central portion 5426 of the second tension member remainparallel to the centerline CL₃ over a portion of the range of motion ofthe second link 5610. Although shown as being a single radius ofcurvature R_(bend), in other embodiments the second guide surface 5621can be a curved surface that is characterized by multiple differentradii of curvature.

When the first tension member 5420 and the second tension member 5440are moved in the same direction (e.g., to produce a yaw motion of theend effector 5460), one of the first distal central portion 5423 or thesecond distal central portion 5433 will move along with rotation of thepulley 5660, and the other of the first distal central portion 5423 orthe second distal central portion 5433 will slide against the outersurface 5661. Typically, the tension member that has the greater wrapangle about the pulley 5660 (i.e., the tension member that has thegreater amount of friction with the outer surface 5661) will cause thepulley 5660 to rotate, and the tension member with the lesser wrap angle(i.e., the tension member that has the lower amount of friction) willslide against the outer surface 5661. In this manner, the pulley 5660advantageously reduces the friction at the area of highest friction.This arrangement allows for efficient operation of the end effector 5460regardless of the pitch orientation of the wrist assembly 5500.

When the wrist assembly 5500 is in the second orientation (FIGS. 21 and24), the first distal central portion 5423 of the first tension member5420 remains within the first curved guide path 5615, and is in contactwith the first guide surface 5616. Moreover, the first distal centralportion 5423 is spaced apart from the pulley 5660. Further, when thewrist assembly 5500 is in the second orientation (FIGS. 21 and 24), thesecond distal central portion 5433 of the second tension member 5440remains within the second curved guide path 5620, and is in contact with(and at least partially wrapped about) the outer surface 5661 of thepulley 5660. Thus, when axial tension is applied to the second tensionmember 5440 for pitch movements or movement of the second tool member5482 for yaw or grip movements, the pulley 5660 rotates along withmovement of the second distal central portion 5433. The rotation of thepulley 5660 is based on contact with the second tension member 5440 atthe outer surface 5661, and reduces friction that would otherwise occurwhen the tension member slides against the surfaces of the second link5610 when tension is applied for pitch, yaw, or grip movements.

In some embodiments, the instrument 5400 is configured such that one ormore pitch tension members (not shown) are additionally provided forassisting other tension members (e.g., the first and second tensionmembers 5420, 5440) with producing pitch rotations and/or for theprimary purpose of producing the pitch movements. The pitch tensionmembers can be coupled to the second link 5610 in such as manner as tocause the second link to rotate with respect to the first link 5510(i.e., a pitch rotation) when the pitch tension member(s) are moved. Inthis manner, the wrist assembly 5500 can be, for instance, a six-tensionmember (or six-cable) configuration (two pitch tension members orportions of pitch tension members controlling the pitch rotation andfour tension members or portions of tension members controlling the yawand grip rotations). In other embodiments any number of pitch tensionmembers can be provided as appropriate to produce and/or assist withproducing pitch movements in the wrist assembly. For example, referringto FIGS. 26-31, diagrammatic illustrations are shown of various portionsof an instrument 6400 that includes a wrist assembly 6500 having a pitchtension member 6455 for producing pitch rotations, according to anembodiment. Instrument 6400 and wrist assembly 6500 generally includethe aspects and preferences of the instruments described above includinginstruments 2400, 3400, 4400 and 5400 and the corresponding wristassemblies, except as discussed below.

In some embodiments, the instrument 6400 or any of the componentstherein are optionally parts of a surgical system that performsminimally invasive surgical procedures, and which can include amanipulator unit, a series of kinematic linkages, a series of cannulas,or the like. The instrument 6400 (and any of the instruments describedherein) can be used in any suitable surgical system, such as the MIRSsystem 1000 shown and described above. The instrument 6400 includes awrist assembly 6500, at least one tension member 6455, and a tool member6462. Although only one tension member 6455 is shown, one or moreadditional tension members can be included. As described herein, theinstrument 6400 is configured such that movement of the tension member6455 produces movement of the wrist assembly 6500 (as indicated by arrowBB shown in FIG. 26).

Referring to FIGS. 26-28, the wrist assembly 6500 includes a proximalfirst link 6510, and a distal second link 6610. The first link 6510 hasa proximal end portion 6511 and a distal end portion 6512. The proximalend portion 6511 is coupled to an instrument shaft (not shown). Althoughthe instrument shaft is not shown in FIGS. 26-31, the proximal endportion 6511 can be coupled to any suitable instrument shaft, such asthe instrument shaft 4410 (FIG. 9) shown and described above along withinstrument 4400. Moreover, the proximal end portion 6511 of the firstlink 6510 can be coupled to the instrument shaft via any suitablemechanism, such as welding, interference fit, adhesive, etc. Asdescribed below, the distal end portion 6512 is rotatably coupled to thesecond link 6610. In this manner, the first link 6510 and the secondlink 6610 form the wrist assembly 6500 having a first axis of rotationA₁ (which functions as a pitch axis; the term pitch is arbitrary) aboutwhich the second link can rotate relative to the first link through anangular range of the wrist assembly.

The proximal first link 6510 defines a first guide path 6515 within andthrough the first link, which extends from the proximal end portion 6511of the first link to its distal end portion 6512. At least a portion ofthe first guide path 6515 is parallel with the centerline CL of theshaft, but is offset from the centerline of the shaft as discussedfurther below. As such, a centerline CU of the first guide path 6515 isoffset from the centerline CL of the shaft by a distance. In someembodiments, the centerline CL of the shaft is coaxial with a centerlineof the first link 6510 and intersects the first axis of rotation A₁.

The second link 6610 has a proximal end portion 6611 and a distal endportion 6612. As described above, the proximal end portion 6611 isrotatably coupled to the distal end portion 6512 of the first link 6510to form a wrist joint. The axis of rotation A₁ is located on thecenterline CL of the shaft and, in some embodiments, on the centerlineof the first link 6510, as well as on the centerline of the second link6610 as shown in FIG. 26. In a first orientation shown in FIGS. 26-28,the centerline CL of the first link 6510, and the centerline of thesecond link 6610 are collinear. Thus, the centerlines of the first andsecond links 6510, 6610 and the wrist assembly 6500 while in the firstorientation of FIGS. 26-28 are collectively represented CL in FIGS.26-28 for simplicity and to avoid confusion with centerlines of pathsand/or other features defined in the wrist assembly 6500. Similar towrist assemblies discussed above, the distal end portion 6612 of thesecond link 6610 includes a connector (not shown) that is coupled to thetool member 6462 such that the tool member 6462 can rotate relative tothe wrist assembly 6500 about a second axis of rotation (not shown)through an angular range. The connector can be any suitable connectorfor rotatably coupling the tool member 6462 to the second link 6610 andforming a tool joint.

Referring to FIGS. 26-28, the second link 6610 defines a second guidepath 6615, a retention pocket 6656, a connection path 6655 and anassembly path 6691. The second guide path 6615 is defined within andthrough a portion of the second link, and extends from the first guidepath 6515 at the proximal end portion 6611 of the second link to theconnection path 6655. The connection path 6655 is defined within andthrough a portion of the second link, and extends between the secondguide path 6615 and the retention pocket 6656. In some embodiments, theconnection path 6655 has a centerline CL₂ that intersects a centerlineCL₁ of the second guide path 6615. A wall 6654 of the second link 6610surrounds a portion of the connection path 6655. The second link 6610defines the retention pocket 6656 as an interior cavity formed withinthe second link 6610, which is coupled to the connection path 6655 atone end of the connection path. In some embodiments, the second link6610 can define a slot opening 6658 that can provide access to theretention pocket 6656, such as for use during installation of thetension member 6455. As also described in further detail below, theretention pocket 6656 is configured to receive and retain therein aretention member 6459 that is coupled to the tension member 6455.Further, the retention pocket 6656 is sized to extend beyond across-section of the connection path 6655 at its connection therewith,so that the wall 6654 surrounding the connection path 6655 forms a stopthat can help retain therein the retention member 6459. Similar to theconnection path 6655, the assembly path 6691 is also defined within andthrough a portion of the second link 6610, and also extends between theretention pocket 6656 and a portion of the second link that is proximateto the centerline CL₁ of the second guide path 6615. However, asdiscussed in greater detail below along with the tension member 6455,the assembly path 6691 is angled away from the connection path 6655 asthe paths extend outward from the retention pocket 6656.

The centerline CL₂ of the connection path 6655 is aligned with acenterline CL₁ of the second guide path 6615 such that the two pathstogether form a combined path for the tension member between the firstguide path 6515 in the first link 6510 and the retention pocket 6656formed within the second link 6610. As such, the connection pathcenterline CL₂ intersects the second guide path centerline CL₁ at theintersection of the two paths. The intersecting centerlines CL₁, CL₂ ofthe aligned paths define a first plane 6605 within the second link 6610.In some embodiments, the first plane 6605 is oriented such that it istransverse with respect to the longitudinal axis of the second link6610. As shown in FIG. 27, the first plane 6605 defined in wristassembly 6500 corresponds with the cross-sectional view line Q-Q. Assuch, the cross-sectional view of FIG. 28 that is taken according toline Q-Q shown in FIG. 27 provides a view of the wrist assembly 6500along the first plane 6605 including the centerline CL₁ of the secondguide path 6615 and the centerline CL₂ of the connection path 6655.

Referring to FIGS. 27 and 29, the assembly path 6691 is not parallel tothe second guide path 6615. Rather, as shown FIG. 29, the assembly path6691 is nonparallel to (or angled away from) the connection path 6655 asit extends outward from the retention pocket 6656. Further, thecenterline CL₃ of the assembly path 6691 is configured to be nonparallelto the connection path centerline CL₂ of the connection path 6655 withina second plane 6609, which is nonparallel to the first plane 6605.Because both the connection path 6655 and the assembly path 6691 connectwith the retention pocket 6656, the centerline CL₃ of the assembly pathforms an insertion angle 6695 with respect to the centerline CL₂ of theconnection path at the retention pocket 6656 when considered from aplane other than from the first plane 6605.

Stated differently, the assembly path 6691 extends outward from theretention pocket 6656 at an insertion angle 6695 that is oriented awayfrom the connection path 6655 and away from the path of the tensionmember 6455 within the second link 6610 along the first plane 6605,which includes the second guide path 6615 and the connection path 6655aligned to form a path between the first guide path 6515 (e.g., a firstlink guide path) and the retention pocket 6656 for the tension member.As discussed further below, the orientation of the assembly path 6691 atthe insertion angle 6695 with respect to the connection path 6655 andthe first plane 6605 allows the tension member 6455 to be installed androuted more easily within the second link 6610 while avoiding damage tothe tension member 6455 during installation. Further, the second linkdefines an open path at inner portions of the second link locatedbetween the connection path 6655 and the assembly path 6691 within theinsertion angle 6695 (see FIG. 29). Stated differently, the inner sideportion of the connection path 6655 and the assembly path 6691 locatedbetween the two paths is open such that tension member 6455 can be movedfrom the assembly path 6691 to the connection path 6655 as appropriateduring installation of the tension member.

Referring to FIGS. 26 and 29-31, the tension member 6455 has a proximalend portion 6456, a distal end portion 6458 that is coupled to aretention member 6459, and a central portion 6457 disposed between theproximal end portion and the distal end portion. The proximal endportion 6456 is located within a portion of the first guide path 6515 ofthe first link 6510. Further, the proximal end portion 6456 is coupledto an instrument shaft (not shown), which is coupled to a housing of atransmission mechanism, such as transmission mechanism 4700 discussedabove. The central portion 6457 is between the distal end portion 6458and the proximal end portion 6456, and is located within the secondguide path 6615 of the second link 6610 and within a portion of theconnection path 6655. The retention member 6459 is connected to thedistal end portion 6458 of the tension member 6455 and is configured tofit within the retention pocket 6656 such that the distal end portion6458 of the tension member extends from retention member 6459 and theretention pocket 6656 to be within the connection path 6655. Theretention member 6459 is sized such that it is larger than the distalend portion 6458 of the tension member at its connection thereto.Further, the retention member 6459 is sized to fit within the retentionpocket 6656 such that the wall 6654 surrounding the connection path 6655forms a stop to assist with retaining the retention member 6459 withinthe retention pocket 6656 when tension is applied to the tension memberalong its longitudinal axis for providing pitch movements of the secondlink 6610 with respect to the first link 6510. Stated differently, theretention member 6459, the retention pocket 6656 and the connection path6655 are configured such that the retention member is unable to movewith the connection path 6655.

Thus, the wrist assembly 6500 is configured to securely retain thetension member 6455 within the connection path 6655 and the second guidepath 6615 during pitch movements in the direction BB shown in FIG. 26,for example, for angular rotations about the first axis A₁ away from thefirst orientation shown in FIG. 26. The retention pocket 6656 securelyretains the retention member 6459 therein based on beneficial features,such as interference with stop features like the wall 6654 surrounding aportion of the connection path 6655, as well as the retention pocket6656 being sized to be larger than the cross-section of the connectionpath 6655, and the retention member being sized to fit within theretention pocket 6656 and also to extend beyond the cross-section of thedistal end portion 6458.

In addition, the wrist assembly 6500 is further configured to improvethe ease of installing the tension member 6455 within the wrist assembly6500 including routing the tension member 6455 through the second link6610 and installing the retention member 6459 within the retentionpocket 6656 and other features that can provide benefits for retainingthe tension member within the second link 6610. Further, the wristassembly 6500 is configured to reduce the likelihood of the tensionmember 6455 being damaged during installation, such as avoiding bends orkinks from forming within the tension member, and reducing thelikelihood of cuts and abrasions to the tension member frominstallation. Such damage to the tension member can induce areas ofstress concentration within the tension member, permit corrosion tooccur more quickly, adversely impact its structural integrity, changeits performance properties, and otherwise degrade the function,longevity and performance of the tension member.

Referring to FIGS. 29-30, the instrument 6400 and the wrist assembly6500 are configured to allow easy installation of the tension member6455 and the retention member 6459 therein along with providing theretention benefits described above, as well as to reduce the likelihoodof damaging the tension member 6455 during installation. As illustratedin FIGS. 29-30, the wrist assembly 6500 and the tension member 6455 areconfigured such that the proximal end portion 6456 and the centralportion 6457 of the tension member 6455 can be: A) inserted through theassembly path 6691 along the assembly path centerline CL₃; and B) theproximal end portion 6456 and the central portion 6457 can be rotateduntil the proximal end portion 6456 is within the first guide path 6515(FIG. 26) and the central portion 6457 is within the second guide path6615, such that the distal end portion 6458 is within the connectionpath 6655 when assembled.

As shown in FIG. 31A, the tension member 6455 can be flexed within itsrange of flexibility based on its modulus of elasticity and othertension member properties at an appropriate bend angle 6495 to assistwith installation of the tension member while avoiding excessive bendingor flexing that can damage the tension member. The tension member 6455cam be installed by threading the proximal end portion 6456 and thecentral portion 6457 into the second link through the exposed slotopening 6658 of the retention pocket 6656. The bend angle 6495 can be anacute angle as shown in FIG. 31A that flexes the tension member withrespect to the retention member 6459 by a small angle to assist withinstallation while avoiding avoid kinking, permanently bending orotherwise damaging the tension member, such as can occur at much largerbend angles. In some embodiments, the bend angle can be more than theinsertion angle 6695. In some embodiments, the bend angle can be thesame as the insertion angle 6695, and in some embodiments the bendangled can be less than the insertion angle 6695. As described above,the assembly path 6691 is configured and oriented with the respect tothe retention pocket such that the assembly path is angled away from theconnection path 6655 as the paths extend outward from the retentionpocket 6656 at insertion angle 6695. In addition, as shown in FIGS. 31Band 31C, the centerline CL₁ of the assembly path can be oriented awayfrom the connection path 6655 such that the assembly path 6691 isaligned as much as possible with the slot opening 6658. As such, aninstallation path is formed through the slot opening 6658 and theretention pocket 6656, and into and through the angled assembly path6691, which avoids flexing the tension member 6455 at large bend anglesor through contoured paths to install the tension member within thewrist assembly 6500.

When the tension member 6455 has been threaded through the assembly path6691 completely such that the retention member 6459 is retained andinstalled within the retention pocket 6656 as shown in FIG. 31C, thetension member can be moved from the assembly path 6691 into theconnection path 6655 through the open spaced between the two paths.Thus, the tension member 6455 along with the retention member 6459 canbe installed within the wrist assembly 6500 without significantlybending or flexing the tension member or routing it through tight bendsthat damage the tension member. In some embodiments (not shown), theretention member 6459 can be coupled to the distal end portion 6458 ofthe tension after the tension member has been partially installed, suchas while in the position shown in FIG. 31B. Doing so can further avoidexcessive bending and flexing of the tension member during installation.However, coupling the retention member 6459 to the tension member 6455after partially installing the tension member can add otherdifficulties, such as increasing the likelihood of damage to the wristassembly 6500 while attaching the retention member or reducing thequality or integrity of the connection between the retention member 6459and the distal end portion 6458 of the tension member.

Many of the benefits and advantages discussed herein along with thevarious embodiments can be applied to other example embodiments shown ordescribed herein, and/or combined in additional other embodiments. Forexample, many of the aspects and features of the wrist assembly 6500pertaining to having one or more tension members configured to providepitch movements can be combined with other embodiments having tensionmembers that provide pitch movements along with movements of the endeffector. For instance, in some embodiments, one or more tension memberssimilar to tension member 6455 of wrist assembly 6500 can be added toanother instrument, such as instrument 5400 and wrist assembly 5500.Said another way, although the instrument 5400 is shown as including afour-cable wrist assembly 5500, in other embodiments the wrist assembly5500 can include two additional pitch cables. In such embodiments, thefour cable ends (e.g., 5421, 5431, 5441, 5451) can be routed alongsimilar friction reducing guide paths as described above, and can bemanipulated to control the grip or yaw rotation of the end effector andtwo additional cable ends (see 7456, 7457) can be manipulated to controlpitch movement. Moreover, in such embodiments the pitch cable (or cableends) can be installed in a manner similar to that described above withreference to the instrument 6400.

For example, FIGS. 32-41 show an instrument 7400 having a wrist assembly7500, according to an embodiment. The instrument generally includes thelow-friction aspects and components of the instruments described aboveincluding instruments 2400, 3400, 4400 and 5400 and the correspondingwrist assemblies, except as discussed below. In particular, theinstrument 7400 includes certain components and features described abovefor instrument 5400 and wrist assembly 5500 (see FIGS. 18-25), and suchcomponents are not described in detail below. Additionally, unlike theinstrument 5400, the instrument 7400 also includes an additional tensionmember (with two proximal end portions, 7456 and 7457) such that thewrist assembly 7500 is a six-cable wrist. The additional guide paths,pitch control and movements of the wrist assembly 7500, as well asinstallation of a third tension member 7455 (e.g., a pitch tensionmember) are discussed below.

The instrument 7400 and wrist assembly 7500 shown in FIGS. 32-42 caninclude any suitable transmission assembly (not shown in FIGS. 32-42),such as the transmission assembly 5700 described above. Additionally,the instrument 7400 includes an instrument shaft 5410, a wrist assembly7500, and an end effector 5460. Referring to FIG. 32, the instrument7400 also includes a first tension member 5420 and a second tensionmember 5440 that couple the transmission assembly to the wrist assembly7500, as described in greater detail above with reference to FIGS.18-25. However, instrument 7400 is configured such that movement of thetension members 5420, 5440 can produce yaw rotation of the end effector5460 about a second axis of rotation A₂ (“yaw axis”), and grip rotationof the tool members of the end effector 5460 about the yaw axis, or anycombination of these movements. In addition, instrument 7400 and wristassembly 7500 includes a third tension member 7455 that, when moved,produces pitch movements by rotating the second link 7610 with respectto the first link 5510 about the first axis, A₁, for a range of angularrotation as described further below. In other embodiments (not shown),pitch movements can be provided by a combination of movements of thefirst and second tension members along with movements of the third pitchtension member.

Referring to FIG. 32, the wrist assembly 7500 includes a first link 5510(proximal first link) and a second link 7610 (e.g., a distal secondlink). The first link 5510 has a proximal end portion 5511 and a distalend portion 5512. The proximal end portion 5511 is coupled to the distalend portion 5412 of the instrument shaft 5410. The distal end portion5512 includes a joint portion 5540 that is rotatably coupled to a matingjoint portion 7640 of the second link 5610. In this manner, the firstlink 5510 and the second link 7610 form the wrist assembly 5500 having afirst axis of rotation A₁ (also referred to as the pitch axis) aboutwhich the second link 7610 can rotate relative to the first link 5510.As shown in FIG. 32, the first link 5510 and the second link 7610 definea longitudinal centerline that intersects the pitch axis A₁ when theinstrument is in a first (or “straight”) orientation, which is collinearwith the shaft centerline CL. As shown in FIG. 35, the first link 5510defines a fifth guide path 7650 and a sixth guide path 7652 that areconfigured to guide portions of the third tension member 7455 asdescribed further below. The fifth guide path 7650 and the sixth guidepath 7652 are similar to the guide paths (e.g., guide channels) shownand described above with reference to FIG. 11.

Referring to FIGS. 32-37, the second link 7610 has a proximal endportion 7611 and a distal end portion 7612. As described above, theproximal end portion 7611 includes a joint portion 7640 that isrotatably coupled to the joint portion 5540 of the first link 5510. Thedistal end portion 7612 of the second link 7610 includes a connector7680 that is coupled to the end effector 5460. In this manner, the firsttool member 5462 and the second tool member 5482 can rotate relative tothe second link 7610 about a second axis of rotation (also referred toas the yaw axis) A₂. In addition to the guide paths for the firsttension member 5420 and the second tension member 5440 (which aresimilar to the curved guide paths 5615, 5620 described above), thesecond link 7610 also defines a fifth guide path 7650, a sixth guidepath 7652, a retention pocket 7656, a connection path 7655, and anassembly path 7691. The fifth guide path 7650 and sixth guide path 7652are each defined within and through a portion of the second link, andeach extends from a corresponding one of the fifth guide path 7650 andsixth guide path 7652 of the second link 5610 to the connection path7655.

As shown in FIGS. 34, 41, and 42, the connection path 7655 is definedwithin and through a portion of the second link 7610, and extendsbetween the retention pocket 7656 and each of the fifth and sixth guidepaths 7650, 7652. In some embodiments, the connection path 7655 has acenterline CL₂ that intersects a centerline CL₁ of each of the fifth andsixth guide paths 7650, 7652 (FIG. 36). Referring to FIGS. 36 and 37, awall 7654 of the second link 7610 surrounds a portion of the connectionpath 7655. The second link 7610 defines the retention pocket 7656 as aninterior cavity formed within the second link 7610, which is coupled toa central portion of the connection path 7655. The second link 7610defines a slot opening 7658 that can provide access to the retentionpocket 7656, such as for use during installation of the third tensionmember 7455. As also described in further detail below, the retentionpocket 7656 is configured to receive and retain therein a retentionmember 7459 that is coupled to the third tension member 7455. Further,the retention pocket 7656 is sized to be larger than a cross-section ofthe connection path 7655, so that the wall 7654 surrounding theconnection path 7655 forms a stop that can help retain therein theretention member 7459. Similar to the connection path 7655, the assemblypath 7691 is also defined within and through a portion of the secondlink 7610, and also extends from the retention pocket 7656 to portionsof the second link that are proximate to the centerline CL₁ of each ofthe fifth and sixth guide paths 7650, 7652. However, as discussed ingreater detail below along with the third tension member 7455, theassembly path 7691 is angled away from the connection path 7655 as thepaths extend outward from the retention pocket 7656.

The centerline CL₂ of the connection path 7655 is aligned with acenterlines CL₁ of the fifth and sixth guide paths 7650, 7652. Thus, theconnection path 7655 and the fifth and sixth guide paths 7650, 7652together form a combined path for the third tension member 7455 betweenthe fifth and sixth guide paths 7650, 7652 in the first link 5510 thatextends through the retention pocket 7656 formed within the second link7610. As such, the connection path centerline, CL₂, intersects thecenterlines CL₁ at the intersection of the connection path 7655 with thefifth and sixth guide paths 7650, 7652. The centerlines CL₁ of the fifthguide path 7650 and the sixth guide path 7652 define a first plane 7605within the second link 7610 (FIG. 39). In some embodiments, the firstplane 7605 is oriented such that it is transverse with respect to thelongitudinal axis of the second link 7610. The centerline CL₂ of theconnection path 7655 can lie within a second plane 7609 within thesecond link 7610 (FIG. 39). The second plane 7609 can be normal to thefirst plane 7605.

Referring to FIGS. 41 and 42, which shows a cross-section of the secondlink 7610 taken along the second plane 7609, the assembly path 7691 isnot parallel to the fifth and sixth guide paths 7650, 7652. Rather, asshown FIG. 41, the assembly path 7691 is nonparallel to (or angled awayfrom) the connection path 7655 as it extends outward from the retentionpocket 7656. Said another way, the centerline CL₃ of the assembly path7691 is configured to be nonparallel to the connection path centerlineCL₂ of the connection path 7655 within a second plane 7609, which isnonparallel to the first plane 7605. Because both the connection path7655 and the assembly path 7691 connect with the retention pocket 7656,the centerline CL₃ of the assembly path forms an insertion angle 7695(e.g., an assembly angle) with respect to the centerline CL₂ of theconnection path at the retention pocket 7656 when considered from aplane other than from the first plane 7605.

Stated differently, the assembly path 7691 extends outward from theretention pocket 7656 at an insertion angle 7695 that is oriented awayfrom the connection path 7655 and away from the fifth and sixth guidepaths 7650, 7652 of the tension member 7455 within the second link 7610along the first plane 7605. The insertion angle 7695 can have anysuitable value, e.g., from five degrees to 45 degrees. As discussedfurther below, the orientation of the assembly path 7691 at theinsertion angle 7695 with respect to the connection path 7655 and thefirst plane 7605 allows the third tension member 7455 to be installedand routed more easily within the second link 7610 while avoiding damageto the third tension member 7455 during installation. Further, thesecond link 7610 defines an open path at inner portions of the secondlink located between the connection path 7655 and the assembly path 7691within the insertion angle 7695 (see FIG. 41). Stated differently, theinner side portion of the connection path 7655 and the assembly path7691 located between the two paths is open such that third tensionmember 7455 can be moved from the assembly path 7691 to the connectionpath 7655 as appropriate during installation of the tension member.

Referring to FIGS. 34, 35, 38 and 39, the third tension member 7455 hasa first proximal end portion 7456, a distal end portion 7458 that iscoupled to a retention member 7459, a first central portion 7493disposed between the first proximal end portion 7456 and the distal endportion 7458, and a second central portion 7494 disposed between thedistal end portion 7458 and a second proximal end portion 7457. Wheninstalled, the first proximal end portion 7456 is located within aportion of the fifth guide path 7650 of the first link 5510. Similarly,the second proximal end portion 7457 is located within a portion of thesixth guide path 7652 of the first link 5510. Further, the first andsecond proximal end portions 7456, 7457 are each routed within aninstrument shaft (not shown), which is coupled to a housing of atransmission mechanism, such as transmission mechanism discussed above.The first central portion 7493 is between the first distal end portion7458 and the proximal end portion 7458, and is located within the fifthguide path 7650 of the second link 7610 and within a portion of theconnection path 7655. The second central portion 7494 is between thesecond proximal end portion 7457 and the distal end portion 7458, and islocated within the sixth guide path 7652 of the second link 7610 andwithin a portion of the connection path 7655.

The retention member 7459 is connected to the distal end portion 7458 ofthe third tension member 7455 and is configured to fit within theretention pocket 7656 such that the distal end portion 7458 of thetension member extends from retention member 7459 and the retentionpocket 7656 to be within the connection path 7655. The retention member7459 is sized such that it is larger than the distal end portion 7458 ofthe tension member at its connection thereto. Further, the retentionmember 7459 is sized to fit within the retention pocket 7656 such thatthe wall 7654 surrounding the connection path 7655 forms a stop toassist with retaining the retention member 7459 within the retentionpocket 7656 when tension is applied to the tension member along itslongitudinal axis (arrow A-B shown in FIG. 35) for providing pitchmovements of the second link 7610 with respect to the first link 5510.Stated differently, the retention member 7459, the retention pocket 7656and the connection path 7655 are configured such that the retentionmember is unable to move with the connection path 7655.

Thus, the wrist assembly 7500 is configured to securely retain the thirdtension member 7455 within the connection path 7655 and the fifth andsixth guide path 7650, 7652 during pitch movements, for example, forangular rotations about the first axis A₁ away from the firstorientation shown in FIGS. 32 and 35. The retention pocket 7656 securelyretains the retention member 7459 therein based on beneficial features,such as interference with stop features like the wall 7654 surrounding aportion of the connection path 7655, as well as the retention pocket7656 being sized to be larger than the cross-section of the connectionpath 7655, and the retention member being sized to fit within theretention pocket 7656 and also to be larger than the cross-section ofthe distal end portion 7458.

In addition, the wrist assembly 7500 is further configured to improvethe ease of installing the third tension member 7455 within the wristassembly 7500 including routing the third tension member 7455 throughthe second link 7610 and installing the retention member 7459 within theretention pocket 7656 and other features that can provide benefits forretaining the tension member within the second link 7610. Further, thewrist assembly 7500 is configured to reduce the likelihood of the thirdtension member 7455 being damaged during installation, such as avoidingbends or kinks from forming within the tension member, and reducing thelikelihood of cuts and abrasions to the tension member frominstallation.

Referring to FIGS. 39-42, the instrument 7400 and the wrist assembly7500 are configured to allow easy installation of the third tensionmember 7455 and the retention member 7459 therein along with providingthe retention benefits described above, as well as to reduce thelikelihood of damaging the third tension member 7455 duringinstallation. As illustrated in FIGS. 39-42, the wrist assembly 7500 andthe tension member 7455 are configured such that the first proximal endportion 7456 and each of the first and second central portions 7493,7494 of the third tension member 7455 can be: A) inserted through theassembly path 7691 along the assembly path centerline CL₂; and B) thefirst and second proximal end portions 7456, 7457 and the first andsecond central portions 7493, 7494 can be rotated until each of thefirst and second proximal end portions 7456, 7457 is within thecorresponding fifth and sixth guide paths 7650, 7652 of the first link5510 (FIG. 35) and the first and second central portions 7493, 7494 areeach within the corresponding fifth and sixth guide paths 7650, 7652,such that the distal end portion 7458 is within the connection path 7655when assembled.

As shown in FIGS. 40 and 42, the third tension member 7455 can be flexedwithin its range of flexibility based on its modulus of elasticity andother tension member properties at an appropriate bend angle to assistwith installation of the tension member while avoiding excessive bendingor flexing that can damage the tension member. The third tension member7455 can be installed by threading the first and second proximal endportions 7456, 7457 and the first and second central portions 7493, 7494into the second link through the exposed slot opening 7658 of theretention pocket 7656. The bend angle 7495 can be an acute angle asshown in FIG. 42 that flexes the tension member with respect to theretention member 7459 by a small angle to assist with installation whileavoiding avoid kinking, permanently bending or otherwise damaging thetension member, such as can occur at much larger bend angles. In someembodiments, the bend angle can be more than the insertion angle 7695.In some embodiments, the bend angle can be the same as the insertionangle 7695, and in some embodiments the bend angled can be less than theinsertion angle 7695.

As described above, the assembly path 7691 is configured and orientedwith the respect to the retention pocket such that the assembly path isangled away from the connection path 7655 as the paths extend outwardfrom the retention pocket 7656 at the insertion angle 7695. In addition,as shown in FIGS. 39-42, the centerline CL₃ of the assembly path can beoriented away from the connection path 7655 such that the assembly path7691 is aligned as much as possible with the slot opening 7658. As such,an installation path is formed through the slot opening 7658 and theretention pocket 7656, and into and through the angled assembly path7691, which avoids flexing the third tension member 7455 at large bendangles or through contoured paths to install the tension member withinthe wrist assembly 7500.

When the third tension member 7455 has been threaded through theassembly path 7691 such that the retention member 7459 is retained andinstalled within the retention pocket 7656 as shown in FIG. 42, thetension member can be moved from the assembly path 7691 into theconnection path 7655 through the open spaced between the two paths.Thus, the third tension member 7455 along with the retention member 7459can be installed within the wrist assembly 7500 without significantlybending or flexing the tension member or routing it through tight bendsthat damage the tension member. In some embodiments (not shown), theretention member can be coupled to the distal end portion of the tensionafter the tension member has been partially installed. Doing so canfurther avoid excessive bending and flexing of the tension member duringinstallation.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Where methods and/or schematics described above indicatecertain events and/or flow patterns occurring in certain order, theordering of certain events and/or operations may be modified. While theembodiments have been particularly shown and described, it will beunderstood that various changes in form and details may be made.

For example, any of the instruments described herein (and the componentstherein) are optionally parts of a surgical assembly that performsminimally invasive surgical procedures, and which can include amanipulator unit, a series of kinematic linkages, a series of cannulas,or the like. Thus, any of the instruments described herein can be usedin any suitable surgical system, such as the MIRS system 1000 shown anddescribed above. Moreover, any of the instruments shown and describedherein can be used to manipulate target tissue during a surgicalprocedure. Such target tissue can be cancer cells, tumor cells, lesions,vascular occlusions, thrombosis, calculi, uterine fibroids, bonemetastases, adenomyosis, or any other bodily tissue. The presentedexamples of target tissue are not an exhaustive list. Moreover, a targetstructure can also include an artificial substance (or non-tissue)within or associated with a body, such as for example, a stent, aportion of an artificial tube, a fastener within the body or the like.

For example, any of the tool members can be constructed from anymaterial, such as medical grade stainless steel, nickel alloys, titaniumalloys or the like. Further, any of the links, tool members, tensionmembers, or components described herein can be constructed from multiplepieces that are later joined together. For example, in some embodiments,a link can be constructed by joining together separately constructedcomponents. In other embodiments however, any of the links, toolmembers, tension members, or components described herein can bemonolithically constructed.

Although the instruments are generally shown as having a second axis ofrotation A₂ that is normal to the first axis of rotation A₁, in otherembodiments any of the instruments described herein can include a secondaxis of rotation A₂ that is offset from the first axis of rotation A₁ byany suitable angle.

Although various embodiments have been described as having particularfeatures and/or combinations of components, other embodiments arepossible having a combination of any features and/or components from anyof embodiments as discussed above. Aspects have been described in thegeneral context of medical devices, and more specifically surgicalinstruments, but inventive aspects are not necessarily limited to use inmedical devices.

For example, in some embodiments an instrument can include a tensionmember that is twisted as described above with reference to theinstrument 5400 and that also has one or more links (e.g., a first linkor a second link) that include and inner guide surface or an outer guidesurface as described above with reference to the instrument 3400. Thus,in some embodiments, the instrument can include a wrist assembly thatdefines a guide surface that can be curved along a longitudinalcenterline and that can have a linear surface along a cross-sectionnormal to the longitudinal centerline.

What is claimed is:
 1. An apparatus, comprising: an instrument shaft, afirst link, a second link, a tool member, and a tension member; thefirst link being coupled to the instrument shaft and comprising a firstguide path having a centerline; the second link comprising a proximalend portion, a distal end portion, and a second guide path, the proximalend portion of the second link being coupled to the first link, thesecond link being rotatable relative to the first link about a firstaxis through an angular range, the distal end portion of the second linkbeing coupled to the tool member, the tool member being rotatablerelative to the second link about a second axis, the second guide pathbeing located between the tool member and the first guide path; and thetension member comprising a first tension member portion, a secondtension member portion, and a third tension member portion, the firsttension member portion being within the first guide path and parallel tothe centerline of the first guide path, the second tension memberportion being coupled to the tool member, the third tension memberportion between the first tension member portion and the second tensionmember portion in the second link, the third tension member portionbeing maintained parallel to the centerline of the first guide paththroughout the angular range of the second link by the second guidepath.
 2. The apparatus of claim 1, wherein: the apparatus includes apulley coupled to the second link; and an outer surface of the pulleydefines a portion of the second guide path.
 3. The apparatus of claim 1,wherein: the second link includes a wall; and the wall defines a portionof the second guide path.
 4. The apparatus of claim 1, wherein: theapparatus includes a pulley coupled to the second link; the second linkincludes a wall; the tension member is in contact with an outer surfaceof the pulley when the second link is at a first angle within theangular range of the second link; and the tension member is in contactwith the wall when the second link is at a second angle within theangular range of the second link different from the first angle.
 5. Theapparatus of claim 4, wherein: the apparatus includes a pin, and the pindefines the first axis; the proximal end portion of the second link iscoupled to the first link by the pin; and the pulley is configured torotate relative to the second link about the pin.
 6. The apparatus ofclaim 1, wherein: the instrument shaft has an axial centerline; thecenterline of the first guide path is offset from the axial centerlineof the instrument shaft by a first distance; the second tension memberportion is parallel to the axial centerline of the instrument shaft andis offset from the axial centerline of the instrument shaft by a seconddistance; and the second distance is less than the first distance.
 7. Anapparatus, comprising: an instrument shaft, a first link, a second link,a tool member, and a tension member; the first link being coupled to theinstrument shaft and comprising a first guide path having a centerline;the second link comprising a proximal end portion, a distal end portion,a second guide path, an inner guide surface, and an outer guide surface,the proximal end portion of the second link being coupled to the firstlink, the second link being rotatable relative to the first link about afirst axis through an angular range, the distal end portion of thesecond link being coupled to the tool member, the tool member beingrotatable relative to the second link about a second axis, the secondguide path being located between the tool member and the first guidepath, and a portion of the second guide path is defined by the innerguide surface and the outer guide surface; and the tension membercomprising a first tension member portion, a second tension memberportion, and a third tension member portion between the first tensionmember portion and the second tension member portion, the first tensionmember portion being within the first guide path and parallel to thecenterline of the first guide path, the second tension member portionbeing coupled to the tool member, and the third tension member portionbeing in contact with the inner guide surface throughout a first portionof the angular range of the second link and being in contact with theouter guide surface throughout a second portion of the angular range ofthe second link.
 8. The apparatus of claim 7, wherein: the third tensionmember portion is spaced apart from the inner guide surface and incontact with the outer guide surface when the second link is in a firstorientation relative to the first link; and the third tension memberportion is spaced apart from the outer guide surface and in contact withthe inner guide surface when the second link is in a second orientationrelative to the first link different from the first orientation.
 9. Theapparatus of claim 7, wherein: the tension member includes a fourthtension member portion between the first tension member portion and thethird tension member portion; and the fourth tension member portion isparallel to the centerline of the first guide path throughout theangular range of the second link.
 10. The apparatus of claim 7, wherein:the inner guide surface of the second link is an outer surface of apulley coupled to the second link.
 11. The apparatus of claim 10,wherein: the instrument shaft has an axial centerline; the centerline ofthe first guide path is offset from the axial centerline of theinstrument shaft by an offset distance; the outer surface of the pulleydefines a pulley radius; and the pulley radius is equal to the offsetdistance.
 12. The apparatus of claim 7, wherein: the outer guide surfaceof the second link is a wall of the second link.
 13. An apparatus,comprising: an instrument shaft, a first link, a second link, a toolmember, and a tension member; the first link being coupled to theinstrument shaft having an axial centerline and comprising a first guidepath having a centerline, the centerline of the first guide path isoffset from the axial centerline of the instrument shaft by an offsetdistance; the second link comprising a proximal end portion, a distalend portion, a second guide path, and an inner guide surface, theproximal end portion of the second link being coupled to the first link,the second link being rotatable relative to the first link about a firstaxis through an angular range, the distal end portion of the second linkbeing coupled to the tool member, the tool member being rotatablerelative to the second link about a second axis, the second guide pathbeing located between the tool member and the first guide path, theinner guide surface defining a portion of the second guide path, and anouter radius of the inner guide surface is equal to the offset distance;and the tension member comprising a first tension member portion, asecond tension member portion, and a third tension member portionbetween the first tension member portion and the second tension memberportion, the first tension member portion being within the first guidepath and parallel to the centerline of the first guide path, the secondtension member portion being coupled to the tool member, and the thirdtension member portion being in contact with the inner guide surfacethroughout a portion of the angular range of the second link.
 14. Theapparatus of claim 13, wherein: the portion of the second guide path isa first portion of the second guide path; the second link includes anouter guide surface; and the outer guide surface defines a secondportion of the second guide path.
 15. The apparatus of claim 14,wherein: the portion of the angular range is a first portion of theangular range of the second link; and the third tension member portionis in contact with the outer guide surface throughout a second portionof the angular range of the second link that is different from the firstportion of the angular range.
 16. The apparatus of claim 13, wherein:the second tension member portion is parallel to the axial centerline ofthe instrument shaft and is offset from the axial centerline of theinstrument shaft by a second distance that is less than the offsetdistance.
 17. The apparatus of claim 13, wherein: the tension membercomprises a fourth tension member portion between the first tensionmember portion and the third tension member portion; and the fourthtension member portion is parallel to the centerline of the first guidepath throughout the angular range of the second link.
 18. The apparatusof claim 13, wherein: the tool member is a first tool member, a thirdguide path is defined within the first link, a fourth guide path isdefined within the second link between a second tool member and thethird guide path, the distal end portion of the second link is coupledto the second tool member, and the tension member is a first tensionmember; the apparatus further comprises a second tension member having afifth tension member portion, a sixth tension member portion, and aseventh tension member portion; the fifth tension member portion iswithin the third guide path; the sixth tension member portion is coupledto the second tool member; and the seventh tension member portion isparallel to a centerline of the third guide path throughout the angularrange.
 19. An apparatus, comprising: an instrument shaft, a first link,a second link, a tool member, and a tension member; the first link beingcoupled to the instrument shaft having an axial centerline andcomprising a first guide path having a centerline, the centerline of thefirst guide path is offset from the axial centerline of the instrumentshaft by an offset distance; the second link comprising a proximal endportion, a distal end portion, a second guide path, and an outer guidesurface, the proximal end portion of the second link being coupled tothe first link, the second link being rotatable relative to the firstlink about a first axis through an angular range, the distal end portionof the second link being coupled to the tool member, the tool memberbeing rotatable relative to the second link about a second axis, thesecond guide path being located between the tool member and the firstguide path, the outer guide surface defining a portion of the secondguide path; and the tension member comprising a first tension memberportion, a second tension member portion, a third tension memberportion, and a fourth tension member portion, the first tension memberportion being within the first guide path and parallel to the centerlineof the first guide path, the second tension member portion being coupledto the tool member, the third tension member portion between the firsttension member portion and the second tension member portion and beingin the second link, the third tension member portion being maintainedparallel to the centerline of the first guide path during a portion ofthe angular range of the second link by a radius of curvature of theouter guide surface.
 20. The apparatus of claim 19, wherein: the portionof the second guide path is a first portion of the second guide path;the second link includes an inner guide surface; and the inner guidesurface defines a second portion of the second guide path.
 21. Theapparatus of claim 20, wherein: the portion of the angular range is afirst portion of the angular range of the second link; and the thirdtension member portion is maintained parallel to the centerline of thefirst guide path during a second portion of the angular range of thesecond link by an outer radius of the inner guide surface.
 22. Theapparatus of claim 20, wherein: an outer radius of the inner guidesurface is equal to the offset distance.
 23. The apparatus of claim 20,wherein: the third tension member portion is spaced apart from the innerguide surface and in contact with the outer guide surface when thesecond link is in a first orientation relative to the first link; andthe third tension member portion is spaced apart from the outer guidesurface and in contact with the inner guide surface when the second linkis in a second orientation relative to the first link different from thefirst orientation.
 24. The apparatus of claim 19, wherein: the secondtension member portion is parallel to the axial centerline of theinstrument shaft and is offset from the axial centerline of theinstrument shaft by a second distance that is less than the offsetdistance.